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  • 1. Ahlström, Christer
    et al.
    Anund, Anna
    Fors, Carina
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Effects of the road environment on the development of driver sleepiness in young male drivers2018In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 112, p. 127-134Article in journal (Refereed)
    Abstract [en]

    Latent driver sleepiness may in some cases be masked by for example social interaction, stress and physical activity. This short-term modulation of sleepiness may also result from environmental factors, such as when driving in stimulating environments. The aim of this study is to compare two road environments and investigate how they affect driver sleepiness. Thirty young male drivers participated in a driving simulator experiment where they drove two scenarios: a rural environment with winding roads and low traffic density, and a suburban road with higher traffic density and a more built-up roadside environment. The driving task was essentially the same in both scenarios, i.e. to stay on the road, without much interaction with other road users. A 2 x 2 design, with the conditions rural versus suburban, and daytime (full sleep) versus night-time (sleep deprived), was used. The results show that there were only minor effects of the road environment on subjective and physiological indicators of sleepiness. In contrast, there was an increase in subjective sleepiness, longer blink durations and increased EEG alpha content, both due to time on task and to night-time driving. The two road environments differed both in terms of the demand on driver action and of visual load, and the results indicate that action demand is the more important of the two factors. The notion that driver fatigue should be countered in a more stimulating visual environment such as in the city is thus more likely due to increased task demand rather than to a richer visual scenery. This should be investigated in further studies.

  • 2. Ahlström, Christer
    et al.
    Anund, Anna
    Fors, Carina
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    The effect of daylight versus darkness on driver sleepiness: a driving simulator study2018In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27, no 3, article id e12642Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness studies are often carried out with alert drivers during daytime and sleep-deprived drivers during night-time. This design results in a mixture of different factors (e.g. circadian effects, homeostatic effects, light conditions) that may confound the results. The aim of this study was to investigate the effect of light conditions on driver sleepiness. Thirty young male drivers (23.6 ± 1.7 years old) participated in a driving simulator experiment where they drove on a rural road. A 2 × 2 design was used with the conditions daylight versus darkness, and daytime (full sleep) versus night-time (sleep deprived). The results show that light condition had an independent effect on the sleepiness variables. The subjective sleepiness measured by Karolinska Sleepiness Scale was higher, lateral position more left-oriented, speed lower, electroencephalogram alpha and theta higher, and blink durations were longer during darkness. The number of line crossings did not change significantly with light condition. The day/night condition had profound effects on most sleepiness indicators while controlling for light condition. The number of line crossings was higher during night driving, Karolinska Sleepiness Scale was higher, blink durations were longer and speed was lower. There were no significant interactions, indicating that light conditions have an additive effect on sleepiness. In conclusion, Karolinska Sleepiness Scale and blink durations increase primarily with sleep deprivation, but also as an effect of darkness. Line crossings are mainly driven by the need for sleep and the reduced alertness at the circadian nadir. Lane position is, however, more determined by light conditions than by sleepiness.

  • 3. Ahlström, Christer
    et al.
    Nyström, Marcus
    Holmqvist, Kenneth
    Fors, Carina
    Sandberg, David
    Anund, Anna
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fit-for-duty test for estimation of drivers' sleepiness level: Eye movements improve the sleep/wake predictor2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 26, p. 20-32Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a driver’s sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS ⩾ 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.

  • 4.
    Akerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Hallvig, David
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Anund, Anna
    Fors, Carina
    Schwarz, Johanna F A
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Having to stop driving at night because of dangerous sleepiness - awareness, physiology and behaviour2013In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 22, no 4, p. 380-388Article in journal (Refereed)
    Abstract [en]

    A large number of accidents are due to the driver falling asleep at the wheel, but details of this link have not been studied on a real road. The purpose of the present study was to describe the development of sleepiness indicators, leading to the drive being terminated prematurely by the onboard expert driving instructor because of imminent danger. Eighteen individuals participated during a day drive and a night drive on a motorway (both 90 min). Eight drivers terminated (N) prematurely (after 43 min) because of sleep-related imminent danger [according to the driving instructor or their own judgement (two cases)]. The results showed very high sleepiness ratings (8.5 units on the Karolinska Sleepiness Scale) immediately before termination (<7 at a similar time interval for those 10 who completed the drive). Group N also showed significantly higher levels of sleep intrusions on the electroencephalography/electro-oculography (EEG/EOG) than those who completed the drive (group C). The sleep intrusions were increased in group N during the first 40 min of the night drive. During the day drive, sleep intrusions were increased significantly in group N. The night drive showed significant increases of all sleepiness indicators compared to the day drive, but also reduced speed and driving to the left in the lane. It was concluded that 44% of drivers during late-night driving became dangerously sleepy, and that this group showed higher perceived sleepiness and more sleep intrusions in the EEG/EOG.

  • 5.
    Andreasson, Anna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden; Macquarie University, Australia.
    Schiller, Helena
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Berntson, Erik
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Work and organizational psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Brief report: Contemplate your symptoms and re-evaluate your health. A study on working adults2017In: Journal of Health Psychology, ISSN 1359-1053, E-ISSN 1461-7277Article in journal (Refereed)
    Abstract [en]

    We investigated whether self-ratings of health are affected by a symptom rating. A diary including a one-item self-rating of health ("pre-self-rated health"; 1 = excellent, 7 = very poor), a subsequent 26-item rating of symptoms, and thereafter a second (identical) health rating ("post-self-rated health") was completed by 820 persons 21 times. Self-rated health worsened significantly ( p < .0001) after the symptom rating, from 2.72 pre-self-rated health (95% confidence interval: 2.70-2.74) to 2.77 post-self-rated health (95% confidence interval: 2.75-2.79) and more so in persons who reported more symptoms ( b = .058, p < .05). The results support the notion that subjective health perception is influenced by attending to symptoms, especially so in persons with a high symptom burden.

  • 6. Anund, Anna
    et al.
    Ahlström, Christer
    Fors, Carina
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Are professional drivers less sleepy than non-professional drivers?2018In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 44, no 1, p. 88-95Article in journal (Refereed)
    Abstract [en]

    Objective It is generally believed that professional drivers can manage quite severe fatigue before routine driving performance is affected. In addition, there are results indicating that professional drivers can adapt to prolonged night shifts and may be able to learn to drive without decreased performance under high levels of sleepiness. However, very little research has been conducted to compare professionals and non-professionals when controlling for time driven and time of day.

    Method The aim of this study was to use a driving simulator to investigate whether professional drivers are more resistant to sleep deprivation than non-professional drivers. Differences in the development of sleepiness (self-reported, physiological and behavioral) during driving was investigated in 11 young professional and 15 non-professional drivers.

    Results Professional drivers self-reported significantly lower sleepiness while driving a simulator than nonprofessional drivers. In contradiction, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness. They also drove faster. The reason for the discrepancy in the relation between the different sleepiness indicators for the two groups could be due to more experience to sleepiness among the professional drivers or possibly to the faster speed, which might unconsciously have been used by the professionals to try to counteract sleepiness.

    Conclusion Professional drivers self-reported significantly lower sleepiness while driving a simulator than non-professional drivers. However, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness, and they drove faster.

  • 7. Anund, Anna
    et al.
    Ahlström, Christer
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Rumble strips in centre of the lane and the effect on sleepy drivers2011In: Industrial Health, ISSN 0019-8366, E-ISSN 1880-8026, Vol. 49, no 5, p. 549-558Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to describe the effects of sleep loss on behavioural and subjective indicators of sleepiness on a road containing a milled rumble strip in the centre of the lane. Particular attention was paid to behavioural and subjective indicators of sleepiness when using the centre lane rumble strip, and to possible erratic driving behaviour when hitting a rumble strip. In total 9 regular shift workers drove during the morning hours after a full night shift and after a full night sleep. The order was balanced. The experiment was conducted in a moving base driving simulator on rural roads with a road width of 6.5 and 9 meters. Out of the 1,636 rumble strip hits that occurred during the study, no indications of erratic driving behaviour associated with the jolt caused by making contact with the centre lane rumble strip could be found. Comparing the alert condition with the sleep deprived condition, both the standard deviation of lateral position (SDLP) and the Karolinska Sleepiness Scale (KSS) increased for sleepy drivers. For the two road widths, the drivers drove closer to the centre line on the 6.5-meter road. The KSS and the SDLP increased with time on task. This simulator study indicates that rumble strips in the centre of the lane may be an alternative to centreline and edgeline rumble strips on narrow roads.

  • 8. Anund, Anna
    et al.
    Fors, Carina
    Hallvig, David
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Observer rated sleepiness and real road driving: an explorative study2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 5, article id e64782Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to explore if observer rated sleepiness (ORS) is a feasible method for quantification of driver sleepiness in field studies. Two measures of ORS were used: (1) one for behavioural signs based on facial expression, body gestures and body movements labelled B-ORS, and (2) one based on driving performance e.g. if swerving and other indicators of impaired driving occurs, labelled D-ORS. A limited number of observers sitting in the back of an experimental vehicle on a motorway about 2 hours repeatedly 3 times per day (before lunch, after lunch, at night) observed 24 participant's sleepiness level with help of the two observer scales. At the same time the participant reported subjective sleepiness (KSS), EOG was recorded (for calculation of blink duration) and several driving measure were taken and synchronized with the reporting. Based on mixed model Anova and correlation analysis the result showed that observer ratings of sleepiness based on drivers' impaired performance and behavioural signs are sensitive to extend the general pattern of time awake, circadian phase and time of driving. The detailed analysis of the subjective sleepiness and ORS showed weak correspondence on an individual level. Only 16% of the changes in KSS were predicted by the observer. The correlation between the observer ratings based on performance (D-ORS) and behavioural signs (B-ORS) are high (r = .588), and the B-ORS shows a moderately strong association (r = .360) with blink duration. Both ORS measures show an association (r>0.45) with KSS, whereas the association with driving performance is weak. The results show that the ORS-method detects the expected general variations in sleepy driving in field studies, however, sudden changes in driver sleepiness on a detailed level as 5 minutes is usually not detected; this holds true both when taking into account driving behaviour or driver behavioural signs.

  • 9. Anund, Anna
    et al.
    Fors, Carina
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    van Leeuwen, Wessel M A
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Countermeasures for fatigue in transportation: A review of existing methods for drivers on road, rail, sea and in aviation2015Report (Other academic)
  • 10. Arnetz, Bengt
    et al.
    Frenzel, Lena
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lisspers, Jan
    The brief fatigue syndrome scale: Validation and utilization in fatigue recovery studies2008In: Fatigue Science for Human Health, Springer , 2008, p. 55-66Chapter in book (Other academic)
  • 11.
    Axelsson, John
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Rehman, Javaid-ur
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Ekman, Rolf
    Miller, Gregory E.
    Höglund, Caroline Olgart
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska institutet, Sweden.
    Effects of Sustained Sleep Restriction on Mitogen-Stimulated Cytokines, Chemokines and T Helper 1/ T Helper 2 Balance in Humans2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 12, article id e82291Article in journal (Refereed)
    Abstract [en]

    Background: Recent studies suggest that acute sleep deprivation disrupts cellular immune responses by shifting T helper (Th) cell activity towards a Th2 cytokine profile. Since little is known about more long-term effects, we investigated how five days of sleep restriction would affect pro-inflammatory, chemotactic, Th1- and Th2 cytokine secretion. Methods: Nine healthy males participated in an experimental sleep protocol with two baseline sleep-wake cycles (sleep 23.00 - 07.00 h) followed by 5 days with restricted sleep (03.00 - 07.00 h). On the second baseline day and on the fifth day with restricted sleep, samples were drawn every third hour for determination of cytokines/chemokines (tumor necrosis factor alpha (TNF-alpha), interleukin (IL) -1 beta, IL-2, IL-4 and monocyte chemoattractant protein-1 (MCP-1)) after in vitro stimulation of whole blood samples with the mitogen phytohemagglutinin (PHA). Also leukocyte numbers, mononuclear cells and cortisol were analysed. Results: 5-days of sleep restriction affected PHA-induced immune responses in several ways. There was a general decrease of IL-2 production (p<.05). A shift in Th1/Th2 cytokine balance was also evident, as determined by a decrease in IL2/IL4 ratio. No other main effects of restricted sleep were shown. Two significant interactions showed that restricted sleep resulted in increased TNF-alpha and MCP-1 in the late evening and early night hours (p's<.05). In addition, all variables varied across the 24 h day. Conclusions: 5-days of sleep restriction is characterized by a shift towards Th2 activity (i.e. lower 1L-2/IL-4 ratio) which is similar to the effects of acute sleep deprivation and psychological stress. This may have implications for people suffering from conditions characterized by excessive Th2 activity like in allergic disease, such as asthma, for whom restricted sleep could have negative consequences.

  • 12. Barck-Holst, Peter
    et al.
    Nilsonne, Asa
    Åkerstedt, Torbjorn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Hellgren, Carina
    Reduced working hours and stress in the Swedish social services: A longitudinal study2017In: International Social Work, ISSN 0020-8728, E-ISSN 1461-7234, Vol. 60, no 4, p. 897-913Article in journal (Refereed)
    Abstract [en]

    Stress has been reported among Swedish social workers for over a decade. Survey data from a longitudinal quasi-experimental trial in the public sector of reduced working hours, with a proportional decrease in workload and retained full pay, were used to examine the effect on stress, symptoms of Exhaustion syndrome, psychosocial work characteristics and work-life balance in social workers. Reduced working hours had a positive effect on restorative sleep, stress, memory difficulties, negative emotion, sleepiness, fatigue and exhaustion both on workdays and weekends; on sleep quality on weekends; and on demands, instrumental manager support and work intrusion on private life.

  • 13. Belenky, Gregory
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Wasensten, Nancy J.
    Introduction. Occupational Sleep Medicin2016In: Principles and Practice of Sleep Medicine / [ed] Meir H. Kryger, Thomas Roth, William C. Dement, Elsevier, 2016, 6 uppl., p. 679-681Chapter in book (Other academic)
  • 14.
    Bellavia, Andrea
    et al.
    Karolinska Inst, Inst Environm Med, Unit Nutr Epidemiol.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Bottai, Matteo
    Wolk, Alicja
    Karolinska Inst, Inst Environm Med, Unit Nutr Epidemiol.
    Orsini, Nicola
    Karolinska Inst, Inst Environm Med, Unit Nutr Epidemiol.
    Sleep Duration and Survival Percentiles Across Categories of Physical Activity2014In: American Journal of Epidemiology, ISSN 0002-9262, E-ISSN 1476-6256, Vol. 179, no 4, p. 484-491Article in journal (Refereed)
    Abstract [en]

    The association between long sleep duration and death is not fully understood. Long sleep is associated with low physical activity, which is a strong predictor of death. Our aim was to investigate the association between sleep duration and death across categories of total physical activity in a large prospective cohort of Swedish men and women. We followed a population-based cohort of 70,973 participants (37,846 men and 33,127 women), aged 45-83 years, from January 1998 to December 2012. Sleep duration and physical activity levels were assessed through a questionnaire. We evaluated the association of interest in terms of mortality rates by estimating hazard ratios with Cox regression and in terms of survival by evaluating 15th survival percentile differences with Laplace regression. During 15 years of follow-up, we recorded 14,575 deaths (8,436 men and 6,139 women). We observed a significant interaction between sleep duration and physical activity in predicting death (P < 0.001). Long sleep duration (>8 hours) was associated with increased mortality risk (hazard ratio = 1.24; 95% confidence interval: 1.11, 1.39) and shorter survival (15th percentile difference = -20 months; 95% confidence interval: -30, -11) among only those with low physical activity. The association between long sleep duration and death might be partly explained by comorbidity with low physical activity.

  • 15. Bokenberger, Kathleen
    et al.
    Sjölander, Arvid
    Dahl Aslan, Anna K.
    Karlsson, Ida K.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Pedersen, Nancy L.
    Shift work and risk of incident dementia: a study of two population-based cohorts2018In: European Journal of Epidemiology, ISSN 0393-2990, E-ISSN 1573-7284, Vol. 33, no 10, p. 977-987Article in journal (Refereed)
    Abstract [en]

    This study aimed to investigate the association between shift work and incident dementia in two population-based cohorts from the Swedish Twin Registry (STR). The STR-1973 sample included 13,283 participants born 1926-1943 who received a mailed questionnaire in 1973 that asked about status (ever/never) and duration (years) of shift work employment. The Screening Across the Lifespan Twin (SALT) sample included 41,199 participants born 1900-1958 who participated in a telephone interview in 1998-2002 that asked about night work status and duration. Dementia diagnoses came from Swedish patient registers. Cox proportional-hazards regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI). Potential confounders such as age, sex, education, diabetes, cardiovascular disease and stroke were included in adjusted models. In genotyped subsamples (n = 2977 in STR-1973; n = 10,366 in SALT), APOE epsilon 4 status was considered in models. A total of 983 (7.4%) and 1979 (4.8%) dementia cases were identified after a median of 41.2 and 14.1 years follow-up in the STR-1973 and SALT sample, respectively. Ever shift work (HR 1.36, 95% CI 1.15-1.60) and night work (HR 1.12, 95% CI 1.01-1.23) were associated with higher dementia incidence. Modest dose-response associations were observed, where longer duration shift work and night work predicted increased dementia risk. Among APOE epsilon 4 carriers, individuals exposed to 20 years of shift work and night work had increased dementia risk compared to day workers. Findings indicate that shift work, including night shift work, compared to non-shift jobs is associated with increased dementia incidence. Confirmation of findings is needed.

  • 16. Bokenberger, Kathleen
    et al.
    Ström, Peter
    Aslan, Anna K. Dahl
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Pedersen, Nancy L.
    Shift work and cognitive aging: a longitudinal study2017In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 43, no 5, p. 485-493Article in journal (Refereed)
    Abstract [en]

    Objectives The few studies of shift work and late life cognitive functioning have yielded mixed findings. The aim of the present study is to estimate the association between shift-work experience and change in cognitive performance before and after retirement age among older adults who were gainfully employed. Methods Five hundred and ninety five participants with no dementia were followed up for a mean of 17.6 standard deviation (SD) 8.8 years from a Swedish population-based sample. Participants had self-reported information on any type of shift-work experience (ever/never) in 1984 and measures of cognitive performance (verbal, spatial, memory, processing speed, and general cognitive ability) from up to 9 waves of cognitive assessments during 1986-2012. Night work history (ever/never) from 1998-2002 was available from a subsample (N = 320). Early adult cognitive test scores were available for 77 men. Results In latent growth curve modeling, there were no main effects of any-type or night shift work on the mean scores or rate of change in any of the cognitive domains. An interaction effect between any-type shift work and education on cognitive performance at retirement was noted. Lower-educated shift workers performed better on cognitive tests than lower-educated day workers at retirement. Sensitivity analyses, however, indicated that the interactions appeared to be driven by selection effects. Lower-educated day workers demonstrated poorer cognitive ability in early adulthood than lower-educated shift workers, who may have selected jobs entailing higher cognitive demand. Conclusion There was no difference in late-life cognitive aging between individuals with a history of working shifts compared to those who had typical day work schedules during midlife.

  • 17. Bokenberger, Kathleen
    et al.
    Ström, Peter
    Dahl Aslan, Anna K.
    Johansson, Anna L. V.
    Gatz, Margaret
    Pedersen, Nancy L.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Association Between Sleep Characteristics and Incident Dementia Accounting for Baseline Cognitive Status: A Prospective Population-Based Study2017In: The journals of gerontology. Series A, Biological sciences and medical sciences, ISSN 1079-5006, E-ISSN 1758-535X, Vol. 72, no 1, p. 134-139Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Although research has shown that sleep disorders are prevalent among people with dementia, the temporal relationship is unclear. We investigated whether atypical sleep characteristics were associated with incident dementia while accounting for baseline cognitive functioning.

    METHODS: Screening Across the Lifespan Twin (SALT) study participants were 11,247 individuals from the Swedish Twin Registry who were at least 65 years at baseline (1998-2002). Sleep and baseline cognitive functioning were assessed via the SALT telephone screening interview. Data on dementia diagnoses came from national health registers. Cox regression was performed to estimate hazard ratios for dementia.

    RESULTS: After 17 years of follow-up, 1,850 dementia cases were identified. Short (≤6 hours) and extended (>9 hours) time in bed (TIB) compared to the middle reference group (hazard ratio = 1.40, 95% confidence interval = 1.06-1.85; hazard ratio = 1.11, 95% confidence interval = 1.00-1.24, respectively) and rising at 8:00 AM or later compared to earlier rising (hazard ratio = 1.12, 95% confidence interval = 1.01-1.24) were associated with higher dementia incidence. Bedtime, sleep quality, restorative sleep, and heavy snoring were not significant predictors. Findings stratified by baseline cognitive status indicated that the association between short TIB and dementia remained in those cognitively intact at the start.

    CONCLUSIONS: Short and extended TIB and delayed rising among older adults predicted increased dementia incidence in the following 17 years. The pattern of findings suggests that extended TIB and late rising represent prodromal features whereas short TIB appeared to be a risk factor for dementia.

  • 18. Bonde, Jens Peter
    et al.
    Hansen, Johnni
    Kolstad, Henrik A.
    Mikkelsen, Sigurd
    Olsen, Jorgen H.
    Blask, David E.
    Harma, Mikko
    Kjuus, Helge
    de Koning, Harry J.
    Olsen, Jorn
    Moller, Morten
    Schernhammer, Eva S.
    Stevens, Richard G.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Work at night and breast cancer - report on evidence-based options for preventive actions2012In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 38, no 4, p. 380-390Article in journal (Refereed)
    Abstract [en]

    In 2007, the International Agency for Research on Cancer classified shift work involving circadian disruption as probably carcinogenic to humans (group 2A), primarily based on experimental and epidemiologic evidence for breast cancer. In order to examine options for evidence-based preventive actions, 16 researchers in basic, epidemiological and applied sciences convened at a workshop in Copenhagen 26-27 October 2011. This paper summarizes the evidence from epidemiological and experimental studies and presents possible recommendations for prevention of the effects of night work on breast cancer. Among those studies that quantified duration of shift work, there were statistically significant elevations in risk only after about 20 years working night shift. It is unclear from these studies whether or not there is a modest but real elevated risk for shorter durations. Hence, restriction of the total number of years working night shift could be one future preventive recommendation for shift workers. The diurnal secretion of melatonin by the pineal gland with peak in secretory activity during the night is a good biochemical marker of the circadian rhythm. Disruption of the diurnal melatonin secretion pattern can be diminished by restricting the number of consecutive night shifts. Reddish light and reduced light intensity during work at night could potentially help diminish the inhibitory activity of light with strong intensity on the melatonin secretion, but further mechanistic insight is needed before definite recommendations can be made. Earlier or more intensive mammography screening among female night shift worker is not recommended because the harm benefit ratio in this age group may not be beneficial. Preventive effects of melatonin supplementation on breast cancer risk have not been clearly documented, but may be a promising avenue if a lack of side effects can be shown even after long-term ingestion. Women with previous or current breast cancer should be advised not to work night shifts because of strong experimental evidence demonstrating accelerated tumor growth by suppression of melatonin secretion. Work during the night is widespread worldwide. To provide additional evidence-based recommendations on prevention of diseases related to night shift work, large studies on the impact of various shift schedules and type of light on circadian rhythms need to be conducted in real work environments.

  • 19. Bränström, Richard
    et al.
    Kvillemo, Pia
    Åkerstedt, Torbjörn
    Karolinska Institute, Sweden.
    Effects of mindfulness training on levels of cortisol in cancer patients2013In: Psychosomatics, ISSN 0033-3182, E-ISSN 1545-7206, Vol. 54, no 2, p. 158-164Article in journal (Refereed)
    Abstract [en]

    Objective: The aims of this study were to examine the effects of a mindfulness-based stress reduction (MBSR) training intervention among cancer patients on levels of salivary cortisol, and further to explore if changes in psychological variables mediate intervention effects on cortisol.

    Methods: Patients with a previous cancer diagnosis (n = 71) were recruited and randomized into an intervention group or a waiting-list control group. The intervention consisted of an 8-week MBSR training course.

    Results: There were no overall effects of the intervention on cortisol levels at 3-month or 6-month follow-up. However, a significant effect of moderation was found showing a different intervention effect on awakening cortisol among participants with varying baseline level of cortisol. Among those with initial low levels of cortisol, there was an increase from baseline to 3-month follow-up, and among those with initial high levels there was a decreased level of cortisol at 3-month follow-up. There was no association between changes in psychological outcomes and cortisol levels.

    Conclusions: The results suggest an adjustment of cortisol levels as a result of MBSR. The study gives preliminary support indicating that MBSR can influence the hypothalamic-pituitary-adrenocortical (HPA) axis functioning. The importance of these findings for future research in the field of mindfulness and stress reduction among cancer patients are discussed.

  • 20. Dahlgren, A.
    et al.
    van Leeuwen, Wessel M. A.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kircher, A.
    Lüthöft, M.
    Barnett, M.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fatiqueat sea: a simulator study of sleepiness, sleep and neurobehavioural performance during different watch schedules2013Conference paper (Refereed)
  • 21.
    Dahlgren, Anna
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology. National Institute for Psychosocial Medicine, Stockholm.
    Kecklund, Göran
    National Institute for Psychosocial Medicine, Stockholm.
    Åkerstedt, Torbjörn
    National Institute for Psychosocial Medicine, Stockholm.
    Overtime work and its effects on sleep, sleepiness, cortisol and blood pressure in an experimental field study2006In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 32, no 4, p. 318-327Article in journal (Refereed)
    Abstract [en]

    Objectives Previous studies of long workhours and their effects on stress, sleep, and health show inconclusive results. This inconclusiveness may be partly due to methodological problems such as the use of between-group designs or comparisons before and after reorganizations. In addition, stress is usually a confounder. A within-person design was used to examine the effects of working 8- or 12-hour shifts in the absence of additional stress. Methods In an experimental field study, 16 white-collar workers [9 women, mean age 45.9 (SD 15) years] undertook one workweek with normal workhours (8 hours) and 1 week of overtime with 4 extra hours of regular worktasks (12 hours). The participants wore actigraphs, rated sleepiness (Karolinska Sleepiness Scale) and stress throughout the day, and rated workload and how exhausted they felt. Saliva samples were collected on Mondays and Thursdays for cortisol analysis. On these days, ambulatory heart rate and blood pressure were also measured for 24 hours. Results Overtime was associated with higher levels of exhaustion. Sleepiness showed a significant interaction between conditions, with higher levels at the end of the workweek featuring overtime. Total sleep time was shorter in the overtime week. There were no significant differences between ratings of stress and workload. Cortisol showed a circadian variation but no main effect of condition. Conclusions One week of overtime work with a moderate workload produced no main effects on physiological stress markers. Nevertheless, sleep was negatively affected, with shorter sleeps during overtime work and greater problems with fatigue and sleepiness.

  • 22.
    Dahlgren, Anna
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology. National Institute for Psychosocial Medicine.
    Åkerstedt, Torbjörn
    National Institute for Psychosocial Medicine.
    Kecklund, Göran
    National Institute for Psychosocial Medicine.
    Individual differences in the diurnal cortisol response to stress2004In: Chronobiology International, ISSN 0742-0528, E-ISSN 1525-6073, Vol. 21, no 6, p. 913-922Article in journal (Refereed)
    Abstract [en]

    The objectives of this study were to explore individual differences associated with diverse reactions in cortisol secretion under different stress levels. This study was part of a larger project concerning working hours and health. Thirty-four whitecollar workers participated under two different conditions; one work week with a high stress level (H) and one with a lower stress level (L) as measured through self-rated stress during workdays. Based on the morning cortisol concentration during a workday subjects were divided into two groups. One group consisted of subjects whose morning level of cortisol increased in response to the high-stress week, compared to their morning levels in the low-stress condition (Group 1). The other group consisted of subjects whose morning cortisol response was the opposite, with a lower level under the high stress condition (Group 2). Subjects wore actiwatches, completed a sleep diary, and rated their sleepiness and stress for one work week in each condition, i.e., high and low stress. Saliva samples for measures of cortisol were collected on a Wednesday. Group 2 reported higher workload, fatigue, and exhaustion during both weeks. Since there were no differences in perceived stress, neither within nor between groups, the data indicate that there are other factors influencing morning cortisol. The results suggest that one component modulating the cortisol response might be the level of exhaustion, probably related to work overload. Higher levels of stress in exhausted individuals might suppress morning cortisol levels.

  • 23.
    Danielsson, Maria
    et al.
    Swedish National Board of Health and Welfare, Stockholm, Sweden.
    Heimerson, Inger
    Swedish National Board of Health and Welfare, Stockholm, Sweden.
    Lundberg, Ulf
    Stockholm University, Faculty of Social Sciences, Centre for Health Equity Studies (CHESS). Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Perski, Aleksander
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Stefansson, Claes-Göran
    Swedish National Board of Health and Welfare, Stockholm, Sweden.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Psychosocial stress and health problems: Health in Sweden: The National Public Health Report 2012. Chapter 62012In: Scandinavian Journal of Public Health, ISSN 1403-4948, E-ISSN 1651-1905, Vol. 40, no 9 suppl, p. 121-134Article in journal (Other academic)
    Abstract [en]

    Stress can be defined as an imbalance between demands placed on us and our ability to manage them. The body’s stress system is adapted to confront sudden physical threats. Today, however, we are increasingly exposed to prolonged mental and psychosocial stress. Prolonged stress can give rise to a range of problems: poor performance, chronic fatigue, disinterest, dejection, memory disturbances, sleep problems, numbness and diffuse muscle pains. These symptoms may eventually be followed by depression, post-traumatic stress disorder and chronic fatigue syndrome, and ultimately chronic pain conditions, cardiovascular disease and diabetes. Sleep is a vital counterbalance to stress as it enables the body to recover properly. Good sleep is thus essential to our ability to cope with stress and stay healthy.

    The decline in the mental wellbeing of the population since the 1980s has been accompanied by a rise in the number of pain complaints. A similar development in respect of symptoms such as anxiousness, nervousness and anxiety, constant fatigue and neck and shoulder pain and sleeping problems has been observed in the population. This increase, which continued throughout the 1990s and culminated in 2001, was followed by a slight fall. However, there was no decline among young people in the early 2000s. Rather, the number of complaints continued to increase.

    Since the mid-1990s, the proportion of people suffering from stress symptoms has risen and fallen in step with employment levels. Since the beginning of the 1980s, growing numbers of people in gainful employment have experienced their work as hectic and mentally taxing. This may indicate that the balance between healthy and unhealthy factors impacting the actively employed has tilted towards less favourable conditions. Mental stress at work has increased among women and men, particularly among county council employees. Repeated organisational restructuring may explain why hectic and mentally taxing work has become more commonplace. Mental ill-health along with musculoskeletal disorders are the most frequent diagnoses in connection with newly granted disability pensions. Sickness absence trends largely reflect the trend in stress symptoms.

  • 24. Dawson, Drew
    et al.
    Ian Noy, Y.
    Härmä, Mikko
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Belenky, Gregory
    Modelling fatigue and the use of fatigue models in work settings2011In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 43, no 2, p. 549-564Article in journal (Refereed)
    Abstract [en]

    In recent years, theoretical models of the sleep and circadian system developed in laboratory settings have been adapted to predict fatigue and, by inference, performance. This is typically done using the timing of prior sleep and waking or working hours as the primary input and the time course of the predicted variables as the primary output. The aim of these models is to provide employers, unions and regulators with quantitative information on the likely average level of fatigue, or risk, associated with a given pattern of work and sleep with the goal of better managing the risk of fatigue-related errors and accidents/incidents. The first part of this review summarises the variables known to influence workplace fatigue and draws attention to the considerable variability attributable to individual and task variables not included in current models. The second part reviews the current fatigue models described in the scientific and technical literature and classifies them according to whether they predict fatigue directly by using the timing of prior sleep and wake (one-step models) or indirectly by using work schedules to infer an average sleep-wake pattern that is then used to predict fatigue (two-step models). The third part of the review looks at the current use of fatigue models in field settings by organizations and regulators. Given their limitations it is suggested that the current generation of models may be appropriate for use as one element in a fatigue risk management system. The final section of the review looks at the future of these models and recommends a standardised approach for their use as an element of the 'defenses-in-depth' approach to fatigue risk management.

  • 25. Di Milia, Lee
    et al.
    Rogers, Naomi L.
    Åkerstedt, Torbjorn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sleepiness, long distance commuting and night work as predictors of driving performance2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 9, p. e45856-Article in journal (Refereed)
    Abstract [en]

    Few studies have examined the effect of working night shift and long distance commuting. We examined the association between several sleep related and demographic variables, commuting distance, night work and use of mobile phones on driving performance. We used a prospective design to recruit participants and conducted a telephone survey (n = 649). The survey collected demographic and journey details, work and sleep history and driving performance concerning the day the participant was recruited. Participants also completed the Karolinska Sleepiness Scale and the Epworth Sleepiness Scale. Night workers reported significantly more sleepiness, shorter sleep duration and commuting longer distances. Seven variables were significant predictors of lane crossing. The strongest predictor was acute sleepiness (OR = 5.25, CI, 1.42-19.49, p < 0.01) followed by driving >= 150 kms (OR = 3.61, CI, 1.66-7.81, p < 0.001), obtaining less than 10 hours sleep in the previous 48 hours (OR = 2.58, CI, 1.03-6.46, p < 0.05), driving after night shift (OR = 2.19, CI, 1.24-3.88, p < 0.001), being <43 years old (OR = 1.95, CI, 1.11-3.41, p < 0.05) and using mobile phones during the journey (OR = 1.90, CI, 1.10-3.27, p < 0.05). Sleep related variables, long-distance commuting and night work have a major impact on lane crossing. Several interventions should be considered to reduce the level of sleepiness in night workers.

  • 26. Eckerberg, Berndt
    et al.
    Lowden, Arne
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Nagai, Roberta
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Melatonin treatment effects on adolescent students' sleep timing and sleepiness in a placebo-controlled crossover study2012In: Chronobiology International, ISSN 0742-0528, E-ISSN 1525-6073, Vol. 29, no 9, p. 1239-1248Article in journal (Refereed)
    Abstract [en]

    During the last few decades, the incidence of sleep-onset insomnia, due to delay of circadian phase, has increased substantially among adolescents all over the world. We wanted to investigate whether a small dose of melatonin given daily, administered in the afternoon, could advance the sleep timing in teenagers. Twenty-one students, aged 14-19 yrs, with sleep-onset difficulties during school weeks were recruited. The study was a randomized, double blind, placebo (PL)-controlled crossover trial, lasting 5 wks. During the first 6 d in wks 2 and 4, the students received either PL or melatonin (1 mg) capsules between 16:30 and 18:00 h. During the first 6 d of wk 5, all students received melatonin. Wks 1 and 3 were capsule-free. In the last evening of each week and the following morning, the students produced saliva samples at home for later melatonin analysis. The samples were produced the same time each week, as late as possible in the evening and as early as possible in the morning. Both the student and one parent received automatic mobile text messages 15 min before saliva sampling times and capsule intake at agreed times. Diaries with registration of presumed sleep, subjective sleepiness during the day (Karolinska Sleepiness Scale, KSS) and times for capsule intake and saliva samplings were completed each day. Primary analysis over 5 wks gave significant results for melatonin, sleep and KSS. Post hoc analysis showed that reported sleep-onset times were advanced after melatonin school weeks compared with PL school weeks (p  <  .005) and that sleep length was longer (p  <  .05). After the last melatonin school week, the students fell asleep 68 min earlier and slept 62 min longer each night compared with the baseline week. Morning melatonin values in saliva diminished compared with PL (p  <  .001) and evening values increased (p  <  .001), indicating a possible sleep phase advance. Compared with PL school weeks, the students reported less wake up (p  <  .05), less school daytime sleepiness (p  <  .05) and increased evening sleepiness (p  <  .005) during melatonin weeks. We conclude that a small dose of melatonin given daily, administered in the afternoon, could advance the sleep timing and make the students more alert during school days even if they continued their often irregular sleep habits during weekends.

  • 27. Filtness, Ashleigh J.
    et al.
    Anund, Anna
    Fors, Carina
    Ahlström, Christer
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud University Nijmegen, Netherlands.
    Sleep-related eye symptoms and their potential for identifying driver sleepiness2014In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 23, no 5, p. 568-575Article in journal (Refereed)
    Abstract [en]

    The majority of individuals appear to have insight into their own sleepiness, but there is some evidence that this does not hold true for all, for example treated patients with obstructive sleep apnoea. Identification of sleep-related symptoms may help drivers determine their sleepiness, eye symptoms in particular show promise. Sixteen participants completed four motorway drives on two separate occasions. Drives were completed during daytime and night-time in both a driving simulator and on the real road. Ten eye symptoms were rated at the end of each drive, and compared with driving performance and subjective and objective sleep metrics recorded during driving. 'Eye strain', 'difficulty focusing', 'heavy eyelids' and 'difficulty keeping the eyes open' were identified as the four key sleep-related eye symptoms. Drives resulting in these eye symptoms were more likely to have high subjective sleepiness and more line crossings than drives where similar eye discomfort was not reported. Furthermore, drivers having unintentional line crossings were likely to have 'heavy eyelids' and 'difficulty keeping the eyes open'. Results suggest that drivers struggling to identify sleepiness could be assisted with the advice 'stop driving if you feel sleepy and/or have heavy eyelids or difficulty keeping your eyes open'.

  • 28. Flo, Elisabeth
    et al.
    Pallesen, Stale
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Mageroy, Nils
    Moen, Bente Elisabeth
    Gronli, Janne
    Nordhus, Inger Hilde
    Bjorvatn, Bjorn
    Shift-related sleep problems vary according to work schedule2013In: Occupational and Environmental Medicine, ISSN 1351-0711, E-ISSN 1470-7926, Vol. 70, no 4, p. 238-245Article in journal (Refereed)
    Abstract [en]

    Objectives Shift-related sleep and sleepiness problems may be due to characteristics of both shifts (ie, day, evening and night shifts) and work schedules (ie, permanent vs rotational schedules). The Bergen Shift Work Sleep Questionnaire (BSWSQ) was used to investigate associations between shift-related sleep problems and work schedules. Methods 1586 nurses completed the BSWSQ. Participants who, in relation to a shift, 'often' or 'always' experienced both a sleep problem and a tiredness/sleepiness problem were defined as having shift-related insomnia (separate for day, evening and night shifts and rest-days). Logistic regression analyses were conducted for day, evening, night, and rest-day insomnia with participants on both permanent and rotational schedules. Results Shift-related insomnia differed between the work schedules. The evening shift insomnia was more prevalent in the two-shift rotation schedule than the three-shift rotation schedule (29.8% and 19.8%, respectively). Night shift insomnia showed higher frequencies among three-shift rotation workers compared with permanent night workers (67.7% and 41.7%, respectively). Rest-day insomnia was more prevalent among permanent night workers compared with two- and three-shift rotations (11.4% compared with 4.2% and 3.6%, respectively). Conclusions The prevalences of shift-related insomnia differed between the work schedules with higher frequencies for three-shift rotations and night shifts. However, sleep problems were present in all shifts and schedules. This suggests that both shifts and work schedules should be considered in the study of shift work-related sleep problems.

  • 29. Garde, Anne Helene
    et al.
    Karlson, Berndt
    Hansen, Åse Marie
    Persson, Roger
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sleep and salivary cortisol2012In: The role of saliva cortisol measurement in health and disease / [ed] Margareta Kristenson, Peter Garvin, Ulf Lundberg, Bentham Science , 2012, p. 116-128Chapter in book (Refereed)
    Abstract [en]

    The aim of the present chapter was to analyze whether measures of cortisol in saliva were associated with measures of sleep and to explore if divergent results were related to underlying differences in theoretic assumptions and methods. Measures of sleep quality included sleep duration, overall sleep quality, difficulty falling asleep, disturbed sleep, and sleep deprivation. Twenty-three papers were found to fulfil the inclusion criteria. Cortisol measures were grouped into single time points at different times during the day, deviations at different time periods during the day, reactivity and recovery after a standardized laboratory test, area under the curve and response to dexamethasone test. A large proportion of the studies included showed nonsignificant findings, which, in several cases, may be a result of low power. The most consistent results were a positive association between sleep duration and single measures of salivary cortisol at awakening, which was observed in 3 studies. In these studies, sleep duration was also associated with low evening cortisol levels, steep diurnal deviation of cortisol and/or high area under the curve. Together these findings suggest that longer sleep duration is related to a more dynamic cortisol secretion. Two of the 6 studies on disturbed or restless sleep showed relations to flat diurnal deviation and low laboratory stress test reactivity. This to some extent corroborates the findings on sleep duration. However, the many nonsignificant findings as well as the theoretical and methodological differences (e.g., heterogeneity in measures) complicate comparisons. Conflicting results may be at least partially due to differences in methods and underlying assumptions.

  • 30.
    Garefelt, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lowden, Arne
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Insomnia among day and shift workers above the arctic circle – associations with stress, light deprivation and underground work2013Conference paper (Other academic)
  • 31.
    Garefelt, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Westerlund, Hugo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Magnusson Hanson, Linda L.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sverke, Magnus
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Work and sleep – a prospective study of psychosocial work factors, physical work factors and work scheduling2014In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 23, no S1, p. 218-218, article id P706Article in journal (Refereed)
  • 32.
    Garefelt, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Westerlund, Hugo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Magnusson Hanson, Linda
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sverke, Magnus
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Work and sleep – the effects of stress, physical work environment and work hours: A prospective study using the SLOSH database2013Conference paper (Other academic)
    Abstract [en]

    METHODS: Data was derived from two waves of SLOSH (The Swedish Longitudinal Occupational Survey of Health), a representative sample of the working population in Sweden. Respondents in the present study sample were gainfully employed in both 2008 (T1) and in 2010 (T2), and without sleep disturbances at T1 (n=5741, 54 % women, 46 % men, aged 24-72 years). Between T1 and T2 a total number of 441 people (8 %) developed sleep disturbances. Logistic regression was made in five hierarchical models with new cases of disturbed sleep as the dependent variable. Factors studied were changes in physical work environment, work hours, demands, control, support and stress between T1 and T2; increased or decreased levels of exposure, as well as consistently high or low levels. RESULTS: In the fully adjusted model, stress showed the strongest association with new cases of disturbed sleep. Increased stress levels had an OR of 2.9 (95% CI 2.0-4.3) and consistently high levels of stress had an OR of 2.8 (1.9-4.2). Increased levels of demands showed a weaker association, OR=1.8 (1.2-2.6), whereas consistently high levels of demands did not show significant results. Decreased levels of social support showed an increased OR of 2.3 (1.6-3.3), as did consistently low levels of social support with an OR of 1.6 (1.1-2.3). Neither changes in control nor changes in work hours showed any significant results. Increased exposure to excessive heat, cold or draught showed a OR of 1.7 (1.1-2.8) whereas changes in heavy physical labour, noise at work, and poor or excessively bright light did not show an association with new cases of sleep disturbances in the fully adjusted model.

  • 33.
    Gerhardsson, Andreas
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Work and organizational psychology.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Emotional working memory in older adults after total sleep deprivation2017In: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 40, no Suppl. 1, p. e110-e110Article in journal (Refereed)
    Abstract [en]

    Introduction: Even though the occurrence of sleep problems increases with age, few studies have focused on the cognitive effects of acute sleep deprivation in elderly. Most previous research indicate that, compared to young, older adults show less impairment in e.g. attention after sleep deprivation. However, little is known of whether the same pattern holds for higher cognitive functions. In addition, while old age is usually related to a general decrease in working memory abilities, performance on working memory tasks may differ depending on the emotional valence of the stimuli, where positive stimuli seem to be beneficial for working memory performance in older adults. The aim of the present study was to investigate the effect of sleep deprivation on emotional working memory in older adults using two levels of working memory load.

    Materials and methods: A healthy sample of 48 old adults (MAge=66.69 years, SDAge=3.44 years) was randomized into a total sleep deprivation group (TSD; n=24) or a sleep control group (SC; n=24). They performed a working memory task (n-back) containing positive, negative and neutral pictures in a low (1-back) and a high (3-back) working memory load condition. Performance was measured as Accuracy (d'), Omissions and Reaction Time (RT).

    Results: For the d' and Omissions we performed two separate 2x2x3 (sleep, working memory load, valence) repeated measures analyses of variance (rmANOVA). For the RTs, we applied a mixed-effects model. For both d' and RT we found no effect of sleep deprivation (Ps > .05). For valence, we found main effects on both d' (F1,46 = 5.56, P=.005) and RT (F1,95.7 = 4.84, P=.01). d' did not differ for positive and neutral pictures, but was in both cases significantly better than for negative pictures. RTs were significantly faster for positive pictures. However, a working memory loadvalence interaction (F1,95.7 = 4.50, P=.01) further revealed an effect of valence in the low, but not in the high load condition. In the low load condition, RTs were faster for positive than for neutral pictures and faster for neutral than for negative pictures. There was no significant effect of Omissions.

    Conclusions: Our results showed that emotional working memory performance was not significantly affected by one night of sleep deprivation in older adults, which contrast what we found in a sample of young adults from the same project. In line with previous research, our results indicate a beneficial effect of positive stimuli on working memory in older adults. This effect was present in both groups and most pronounced for reaction times in the condition with a lower cognitive demand. We can conclude that, among older adults, the working memory performance is not impaired by sleep deprivation and that the benefits of positive stimuli on working memory seem intact. These findings contribute to a better understanding of older adults' cognitive functioning after sleep deprivation.

  • 34.
    Gerhardsson, Andreas
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    The effect of sleep loss on emotional working memory2016In: Abstracts, 2016, Vol. 25(S1), p. 17-18Conference paper (Other academic)
    Abstract [en]

    Objectives: Emotional stimuli differently affect working memory (WM) performance. As sleep deprivation has a known impact on both emotion and WM our aim was to investigate how one night without sleep affects emotional WM performance. Methods: Healthy subjects (n = 56; age 18–30 years) were randomized to a total sleep deprivation (TSD) or a rested control (RC) condition. Subjects rated their affective state and performed a 1 and a 3-back WM task consisting of neutral, positive and negative pictures at 3 pm or 6 pm (balanced) the day after sleep manipulation. Accuracy (d’) and target response time (RT) were used as outcomes. Results: In the TSD condition, subjects rated themselves as less positive (P = 0.006) but not more negative than in the RC condition. In the WM task, TSD had a detrimental effect on accuracy (P = 0.03) regardless of difficulty. Moreover, accuracy was higher in the 1-back than in the 3-back (P < 0.001) and higher for neutral compared to both negative and positive stimuli (Ps < 0.05). RT was faster for positive compared to negative and neutral stimuli (Ps < 0.05). The latter effect was particularly pronounced in the TSD condition as shown by a condition*valence interaction (P < 0.03). Conclusions: One night of total sleep loss impaired emotional WM accuracy. Noticeable, RT was faster for positive stimuli compared to negative and neutral stimuli. This effect was particularly pronounced after sleep loss. This suggests that sleep loss strengthens the opposing effects of positive and negative stimuli on WM performance, possibly due to increased emotion reactivity.

  • 35. Gonçalves, MA
    et al.
    Amici, R
    Peigneux, P
    Luckas, R
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Cirignotta, FC
    Horne, J
    Léger, D
    McNicholas, W
    Partinen, M
    Téran Santos, J
    Grote, L
    The wake-up bus sleep study: falling asleep at the wheel in 19 European countries2014Conference paper (Other academic)
  • 36. Gonçalves, Marta
    et al.
    Amici, Roberto
    Lucas, Raquel
    Åkerstedt, Torbjörn
    ESRS Sleep & Driving Expert Panel, Regensburg, Germany; European Sleep Res Soc, Regensburg, Germany.
    Cirignotta, Fabio
    Horne, Jim
    Léger, Damien
    McNicholas, Walter T
    Partinen, Markku
    Téran-Santos, Joaquín
    Peigneux, Philippe
    Grote, Ludger
    Sleepiness at the wheel across Europe: a survey of 19 countries.2015In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 24, no 3, p. 242-53Article in journal (Refereed)
    Abstract [en]

    The European Sleep Research Society aimed to estimate the prevalence, determinants and consequences of falling asleep at the wheel. In total, 12 434 questionnaires were obtained from 19 countries using an anonymous online questionnaire that collected demographic and sleep-related data, driving behaviour, history of drowsy driving and accidents. Associations were quantified using multivariate logistic regression. The average prevalence of falling asleep at the wheel in the previous 2 years was 17%. Among respondents who fell asleep, the median prevalence of sleep-related accidents was 7.0% (13.2% involved hospital care and 3.6% caused fatalities). The most frequently perceived reasons for falling asleep at the wheel were poor sleep in the previous night (42.5%) and poor sleeping habits in general (34.1%). Falling asleep was more frequent in the Netherlands [odds ratio = 3.55 (95% confidence interval: 1.97; 6.39)] and Austria [2.34 (1.75; 3.13)], followed by Belgium [1.52 (1.28; 1.81)], Portugal [1.34 (1.13, 1.58)], Poland [1.22 (1.06; 1.40)] and France [1.20 (1.05; 1.38)]. Lower odds were found in Croatia [0.36 (0.21; 0.61)], Slovenia [0.62 (0.43; 0.89)] and Italy [0.65 (0.53; 0.79)]. Individual determinants of falling asleep were younger age; male gender [1.79 (1.61; 2.00)]; driving ≥20 000 km year [2.02 (1.74; 2.35)]; higher daytime sleepiness [7.49 (6.26; 8.95)] and high risk of obstructive sleep apnea syndrome [3.48 (2.78; 4.36) in men]. This Pan European survey demonstrates that drowsy driving is a major safety hazard throughout Europe. It emphasizes the importance of joint research and policy efforts to reduce the burden of sleepiness at the wheel for European drivers.

  • 37.
    Hallvig, David
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Anund, Anna
    Fors, Carina
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Karlsson, Johan G.
    Wahde, Mattias
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sleepy driving on the real road and in the simulator-A comparison2012In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 50, p. 44-50Article in journal (Refereed)
    Abstract [en]

    Sleepiness has been identified as one of the most important factors contributing to road crashes. However, almost all work on the detailed changes in behavior and physiology leading up to sleep related crashes has been carried out in driving simulators. It is not clear, however, to what extent simulator results can be generalized to real driving. This study compared real driving with driving in a high fidelity, moving base, driving simulator with respect to driving performance, sleep related physiology (using electroencephalography and electrooculography) and subjective sleepiness during night and day driving for 10 participants. The real road was emulated in the simulator. The results show that the simulator was associated with higher levels of subjective and physiological sleepiness than real driving. However, both for real and simulated driving, the response to night driving appears to be rather similar for subjective sleepiness and sleep physiology. Lateral variability was more responsive to night driving in the simulator, while real driving at night involved a movement to the left in the lane and a reduction of speed, both of which effects were absent in the simulator. It was concluded that the relative validity of simulators is acceptable for many variables, but that in absolute terms simulators cause higher sleepiness levels than real driving. Thus, generalizations from simulators to real driving must be made with great caution.

  • 38.
    Hallvig, David
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Anund, Anna
    Fors, Carina
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud University Nijmegen, The Netherlands.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Real driving at night - predicting lane departures from physiological and subjective sleepiness2014In: Biological Psychology, ISSN 0301-0511, E-ISSN 1873-6246, Vol. 101, p. 18-23Article in journal (Refereed)
    Abstract [en]

    Only limited information is available on how driving performance relates to physiological and subjective sleepiness on real roads. This relation was the focus of the present study. 33 volunteers drove for 90min on a rural road during the afternoon and night in an instrumented car, while electroencephalography and electrooculography and lane departures were recorded continuously and subjective ratings of sleepiness were made every 5min (Karolinska Sleepiness Scale - KSS). Data was analyzed using Bayesian multilevel modeling. Unintentional LDs increased during night driving, as did KSS and long blink durations(LBD). Lateral position moved to the left . LDs were predicted by self-reported sleepiness and LBDs across time and were significantly higher in individuals with high sleepiness. Removal of intentional LDs, enhanced the KSS/LD relation. It was concluded that LDs, KSS, and LBDs are strongly increased during night driving and that KSS predicts LDs.

  • 39. Hedström, A K
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    Olsson, T
    Alfredsson, L
    Shift work influences multiple sclerosis risk.2015In: Multiple Sclerosis, ISSN 1352-4585, E-ISSN 1477-0970, Vol. 21, no 9, p. 1195-9Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: An association between working shift at a young age and subsequent risk for multiple sclerosis (MS) has been observed.

    OBJECTIVE: To investigate whether this finding could be replicated, and to further explore the influence of age at first exposure to shift work.

    METHODS: Using a Swedish population-based, case-control study (2337 cases and 4904 controls), the incidence of MS among subjects whom had worked shifts was compared with that of those whom had not, by calculating odds ratios (ORs) with 95% confidence intervals (CIs) by means of logistic regression.

    RESULTS: The OR of developing MS was 1.5 (95% CI 1.2-1.8) among those whom started working shifts before age 20, whereas a less pronounced association was observed among those whom started working shifts at age 20 or later (OR 1.2; 95% CI 1.1-1.4). The effect of shift work was more pronounced among subjects whom had been exposed at a young age, regardless of the duration between the start of shift work and disease onset.

    CONCLUSION: Some aspects of adolescence seem to be of great importance, regarding the impact of shift work on MS risk. Circadian disruption and sleep deprivation may contribute towards explaining the association; however, the exact mechanisms behind our observations remain to be elucidated.

  • 40. Hedström, Anna Karin
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Hillert, Jan
    Olsson, Tomas
    Alfredsson, Lars
    Shift work at young age is associated with increased risk for multiple sclerosis2011In: Annals of Neurology, ISSN 0364-5134, E-ISSN 1531-8249, Vol. 70, no 5, p. 733-41Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: Environmental factors play a prominent role in multiple sclerosis (MS) etiology. The aim of this study was to investigate the potential association between shift work and MS risk, which has previously never been investigated.

    METHODS: This report is based on 2 population-based, case-control studies, 1 with incident cases (1,343 cases, 2,900 controls) and 1 with prevalent cases (5,129 cases, 4,509 controls). Using logistic regression, the occurrence of MS among subjects who have been exposed to shift work at various ages was compared with that of those who have never been exposed by calculating the odds ratio (OR) with a 95% confidence interval (CI).

    RESULTS: In both studies, there was a significant association between working shift at a young age and occurrence of MS (OR, 1.6; 95% CI, 1.2-2.1 in the incidence study and OR, 1.3; 95% CI, 1.0-1.6 in the prevalence study). In the incident study, the OR of developing MS was 2.0 (95% CI, 1.2-3.6) among those who had worked shifts for 3 years or longer before age 20 years, compared with those who had never worked shifts. The OR for the corresponding comparison in the prevalent study was 2.1 (95% CI, 1.3-3.4).

    INTERPRETATION: The observed association between shift work at a young age and occurrence of MS in 2 independent studies strengthens the notion of a true relationship. Consequences of shift work such as circadian disruption and sleep restriction are associated with disturbed melatonin secretion and enhanced proinflammatory responses and may thus be part of the mechanism behind the association.

  • 41. Hedström, Anna Karin
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Klareskog, Lars
    Alfredsson, Lars
    Relationship between shift work and the onset of rheumatoid arthritis2017In: RMD Open, E-ISSN 2056-5933, Vol. 3, no 2, article id e000475Article in journal (Refereed)
    Abstract [en]

    Background Environmental factors play a prominent role in rheumatoid arthritis (RA) aetiology. Shift work has previously been associated with increased RA risk in females. The aim of this study was to investigate the potential association, including a dose-response association, between permanent night shift work, rotating shift work and day-oriented shift work and risk of developing anticitrullinated peptide antibodies (ACPA)-positive and ACPA-negative RA.

    Methods The present report is based on a population-based, case-control study with incident cases of RA (1951 cases and 2225 controls matched by age, gender and residential area). Using logistic regression, occurrence of RA among subjects who have been exposed to different kinds of shift work was compared with that among those who have never been exposed by calculating the OR with a 95% CI.

    Results Rotating shift work and day-oriented shift work increased the risk of developing ACPA-positive RA (OR 1.3, 95% CI 1.0 to 1.7 and OR 1.3, 95% CI 1.0 to 1.6), but not ACPA-negative RA. Permanent night shift work appeared to be a protective factor both against ACPA-positive RA (OR 0.7, 95% CI 0.6 to 0.9) and ACPA-negative RA (OR 0.8, 95% CI 0.6 to 1.0). For both subsets of RA, significant trends showed a lower risk of developing RA with increasing duration of permanent night shift work (p value for trend 0.002 vs 0.04).

    Conclusions Sleep restriction as a consequence of shift work is associated with several biological effects among which changes in melatonin production may be involved. The present epidemiological findings of a complex relationship between sleep patterns and different forms of RA may be of importance for increasing the understanding of the pathophysiology of RA.

  • 42.
    Ingre, Michael
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    van Leeuwen, Wessel M. A.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Second generation three process model (TMP) of alertness for better assessment of individual risks2013Conference paper (Other academic)
  • 43.
    Ingre, Michael
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    van Leeuwen, Wessel M A
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Klemets, T
    Ullvetter, C
    Hough, S
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Karlsson, D
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Validating and extending the three process model (TPM) of alertness in airline operations.2014In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 23, no S1, p. 264-264, article id P836Article in journal (Other academic)
  • 44.
    Ingre, Michael
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    van Leeuwen, Wessel M. A.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Klemets, Tomas
    Ullvetter, Christer
    Hough, Stephen
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Karlsson, David
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Validating and Extending the Three Process Model of Alertness in Airline Operations.2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 10, p. e108679-Article in journal (Refereed)
    Abstract [en]

    Sleepiness and fatigue are important risk factors in the transport sector and bio-mathematical sleepiness, sleep and fatigue modeling is increasingly becoming a valuable tool for assessing safety of work schedules and rosters in Fatigue Risk Management Systems (FRMS). The present study sought to validate the inner workings of one such model, Three Process Model (TPM), on aircrews and extend the model with functions to model jetlag and to directly assess the risk of any sleepiness level in any shift schedule or roster with and without knowledge of sleep timings. We collected sleep and sleepiness data from 136 aircrews in a real life situation by means of an application running on a handheld touch screen computer device (iPhone, iPod or iPad) and used the TPM to predict sleepiness with varying level of complexity of model equations and data. The results based on multilevel linear and non-linear mixed effects models showed that the TPM predictions correlated with observed ratings of sleepiness, but explorative analyses suggest that the default model can be improved and reduced to include only two-processes (S+C), with adjusted phases of the circadian process based on a single question of circadian type. We also extended the model with a function to model jetlag acclimatization and with estimates of individual differences including reference limits accounting for 50%, 75% and 90% of the population as well as functions for predicting the probability of any level of sleepiness for ecological assessment of absolute and relative risk of sleepiness in shift systems for safety applications.

  • 45.
    Ingre, Michael
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Ekstedt, Mirjam
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Periodic self-rostering in shift work: correspondence between objective work hours, work hour preferences (personal fit), and work schedule satisfaction2012In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 38, no 4, p. 327-336Article in journal (Refereed)
    Abstract [en]

    Objectives The main objective of the present study was to investigate relative personal fit as the association between rated needs and preferences for work hours, on the one hand, and actual work hours, on the other hand, in three groups (hospital, call-center, and police) working with periodic self-rostering. We also examined the association between personal fit and satisfaction with the work schedule and preference for a fixed and regular shift schedule, respectively. Methods We collected questionnaire data and objective work hour data over 6-12 months from the computerized self-rostering system. The response rate of the questionnaire was 69% at the hospital and call-center and 98% among the police. In total, 29 433 shifts for 285 shift workers were included in the study. Data was analyzed by means of mixed ANOVA, Kendal tau correlations and ordinal (proportional odds) logistic regression. Results The results show that evening types worked relatively more hours during the evening and night hours compared to morning types as an indication of relative personal fit. Relative personal fit was also found for long shift, short rest, and morning-, evening- and night-shift frequency, but only personal fit related to morning, evening and night-shift was associated with satisfaction with work hours. Reported conflicts at the workplace about work hours and problems with lack of predictability of time for family/leisure activities, was associated with poor satisfaction and a preference for a fixed shift schedule. Conclusions The present study shows that periodic self-rostering is associated with relative personal fit, in particular with respect to night, evening, and morning work. Personal fit seems to be associated with satisfaction with work hours and may be a moderator of tolerance to shift work exposure.

  • 46.
    Ivarsson, Malena
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Anderson, Martin
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lindblad, Frank
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    The effect of violent and nonviolent video games on heart rate variability, sleep, and emotions in adolescents with different violent gaming habits2013In: Psychosomatic Medicine, ISSN 0033-3174, E-ISSN 1534-7796, Vol. 75, no 4, p. 390-396Article in journal (Refereed)
    Abstract [en]

    Objective To study cardiac, sleep-related, and emotional reactions to playing violent (VG) versus nonviolent video games (NVG) in adolescents with different gaming habits.

    Methods Thirty boys (aged 13-16 years, standard deviation = 0.9), half of them low-exposed (≤1 h/d) and half high-exposed (≥3 h/d) to violent games, played a VG/NVG for 2 hours during two different evenings in their homes. Heart rate (HR) and HR variability were registered from before start until next morning. A questionnaire about emotional reactions was administered after gaming sessions and a sleep diary on the following mornings.

    Results During sleep, there were significant interaction effects between group and gaming condition for HR (means [standard errors] for low-exposed: NVG 63.8 [2.2] and VG 67.7 [2.4]; for high-exposed: NVG 65.5 [1.9] and VG 62.7 [1.9]; F(1,28) = 9.22, p = .005). There was also a significant interaction for sleep quality (low-exposed: NVG 4.3 [0.2] and VG 3.7 [0.3]); high-exposed: NVG 4.4 [0.2] and VG 4.4 [0.2]; F(1,28) = 3.51, p = .036, one sided), and sadness after playing (low-exposed: NVG 1.0 [0.0] and VG 1.4 [0.2]; high-exposed: NVG 1.2 [0.1] and VG 1.1 [0.1]; (F(1,27) = 6.29, p = .009, one sided).

    Conclusions Different combinations of the extent of (low versus high) previous VG and experimental exposure to a VG or an NVG are associated with different reaction patterns-physiologically, emotionally, and sleep related. Desensitizing effects or selection bias stand out as possible explanations.

  • 47. Jansson, Catarina
    et al.
    Alexanderson, Kristina
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Clinically diagnosed insomnia and risk of all-cause and diagnosis-specific sickness absence: a nationwide Swedish prospective cohort study.2013In: Scandinavian Journal of Public Health, ISSN 1403-4948, E-ISSN 1651-1905, Vol. 41, no 7, p. 712-721Article in journal (Refereed)
    Abstract [en]

    Aims: Insomnia is a large health problem. In some prior studies, positive associations between insomnia symptoms and sickness absence have been observed. There is, however, no previous nationwide cohort study of clinically diagnosed insomnia and risk of incident sickness absence. Methods: Prospective nationwide cohort study based on Swedish population-based registers including all 4,956,358 individuals registered as living in Sweden on 31 December 2004/2005, aged 17-64 years, not on disability pension, old-age pension or on-going sickness absence. Those having insomnia inpatient or outpatient care, defined as having at least one admission/specialist visit with a main or secondary diagnosis of disorders of initiating and maintaining sleep [insomnias] (ICD-10: G47.0) during 2000/2001-2005, were compared to those with no such care. All-cause and diagnosis-specific incident sickness absence were followed during 2006-2010. Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were estimated by Cox proportional hazards regression. Results: In models adjusted for prior sickness absence, socio-demographic factors and inpatient and specialized outpatient care, associations between insomnia and increased risks of all-cause sickness absence (IRR 1.18, 95% CI 1.04-1.35) and sickness absence due to mental diagnoses (IRR 1.75, 95% CI 1.36-2.25) were observed. After further adjustment for insomnia medications these associations disappeared. No associations between insomnia and risk of sickness absence due to cancer, circulatory or musculoskeletal diagnoses, or injuries, were observed. Conclusions: In this nationwide cohort study, we observed increased risks of all-cause sickness absence and sickness absence due to mental diagnoses after adjustment for several potential confounders that disappeared after further adjustment for insomnia medications.

  • 48. Kaida, Kosuke
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Takahashi, Masaya
    Vestergren, Peter
    Gillberg, Mats
    Lowden, Arne
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Portin, Christian
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Performance prediction by sleepiness-related subjective symptoms during 26-hour sleep deprivation2008In: Sleep and Biological Rhythms, ISSN 1446-9235, E-ISSN 1479-8425, Vol. 6, p. 234-241Article in journal (Refereed)
    Abstract [en]

    Sleepiness is a major cause of lower productivity and higher risk of accidents in various work situation. Developing sleepiness monitoring techniques is important to important to improve work efficiency and to reduce accident risk, so that people can take a rest/break in appropriate timing before an accident or a mistake occurs. The aim of the present study are (1) to explain subjective sleepiness using sleep-related symptoms, and (2) to examine which symptoms are useful to predict performance errors. Participants were healthy paid volunteers (six males, six females; mean ± SD, 31.5 ± 10.74 years). Participants took part in 26-h sleep deprivation. During sleep deprivation, they carried out several performance tasks every 3 h and an hourly rating of questionnaires to evaluate subjective symptoms including two types of Karolinska Sleepiness Scale (KSS). The present study confirmed that performance errors can be predicted by subjective symptoms. While mental fatigue was correlated to KSS scores linearly, eye-related subjective symptoms showed quadratic correlation to KSS. By taking into consideration this noteworthy relationskap between subjective symptoms and sleepiness, more accurate introspection of sleepiness and performance errors prediction (detection) may be possible.

  • 49.
    Kecklund, Göran
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Ingre, Michael
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    What characterizes good and bad shift schedules?2013Conference paper (Refereed)
  • 50.
    Kecklund, Göran
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Milia, Lee Di
    Axelsson, John
    Lowden, Arne
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    20th International Symposium on Shiftwork and Working Time: Biological Mechanisms, Recovery, and Risk Management in the 24-h Society2012In: Chronobiology International, ISSN 0742-0528, E-ISSN 1525-6073, Vol. 29, no 5, p. 531-536Article in journal (Refereed)
    Abstract [en]

    This dedicated issue of Chronobiology International is devoted to the selected proceedings of the 20th International Symposium on Shift Work and Working Time held in Stockholm, Sweden, 28 June to 1 July 2011. It constitutes the fifth such issue of the journal since 2004 dedicated to the selected proceedings to the meetings of the Working Time Society. The key theme of the 20th Symposium was "Biological Mechanisms, Recovery, and Risk Management in the 24-h Society." The collection of papers of this dedicated issue represents the best of contemporary research on the effects of night and rotating shift schedules on worker health and safety. The contents cover such topics as sleep restriction, injuries, health, and performance of night work and rotating shiftwork, plus light treatment as a countermeasure against the circadian disruption of shiftwork. The majority of the papers are observational field studies, including some of large sample size, and three studies are well-designed laboratory experiments. (Author correspondence: goran.kecklund@stress.su.se ).

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