Marie Söderström

Less effective executive functioning after one night's sleep deprivation

The prefrontal cortex (PFC) is affected negatively by sleep deprivation (SD) and executive functioning is largely dependent on activity in the PFC. Earlier studies have focused on subsystems of executive functioning, and tests of executive functioning have shown both low reliability and low validity. In the present study, 11 healthy volunteers were sleep deprived and compared with 11 healthy controls in a study on effects of one nights SD on integrative executive functioning. Following SD, the performance of subjects on an ecologically valid test, the modified Six Elements Test, was significantly impaired. There were no group differences on psychomotor vigilance, verbal or visuo‐spatial working memory. This extends previous knowledge of performance effects of SD, and may be of special importance for individuals with cognitive work tasks.

Microarousals during sleep are associated with increased levels of lipids, cortisol, and blood pressure.

Objective: Previous work has demonstrated a link between restricted sleep and risk indicators for cardiovascular and metabolic disease, such as levels of cortisol, lipids, and glucose. The present study sought to identify relations between polysomnographic measures of disturbed sleep (frequency of arousals from sleep, total sleep time, and sleep efficiency) and a number of such indicators. A second purpose was to relate the number of arousals to mood, stress, work characteristics, and other possible predictors in daily life. Methods: Twenty-four people (10 men, 14 women; mean age 30 years), high vs. low on burnout, were recruited from a Swedish IT company. Polysomnographically recorded sleep was measured at home before a workday. Blood pressure, heart rate, morning blood sample, and saliva samples of cortisol were measured the subsequent working day. They were also recorded for diary ratings of sleep and stress, and a questionnaire with ratings of sleep, stress, work conditions, and mood was completed. Results: A stepwise regression analysis using sleep parameters as predictors brought out number of arousals as the best predictor of morning cortisol (serum and saliva), heart rate, systolic and diastolic blood pressure, total cholesterol, high-density lipoprotein (HDL)-, low-density lipoprotein (LDL)-cholesterol, and LDL/HDL-ratio. Work stress/unclear boundaries between work and leisure time was the best predictor of arousals among the stress variables. Conclusion: Consistent with sleep restriction experiments, sleep fragmentation was associated with elevated levels of metabolic and cardiovascular risk indicators of stress-related disorders. Number of arousals also seems to be related to workload/stress. ABP = ambulatory blood pressure; DBP = diastolic blood pressure; EEG = electroencephalogram; EMG = electromyographic; EOG = electro-oculogram; HAD = hospital anxiety and depression scale; PSG = polysomnography; SBP = systolic blood pressure; SMBQ = Shirom Melamed burnout questionnaire; TST = total sleep time; WHR = waist to hip ratio.

Sleep Length as a Function of Morning Shift‐Start Time in Irregular Shift Schedules for Train Drivers: Self‐Rated Health and Individual Differences

Forty‐six male train drivers (mean age=46.5, SD=5.1) were recruited to participate in a diary study for 14 consecutive days with questions about their sleep and working hours. A polynomial mixed‐effect regression model showed a curvilinear relation (p <. 001) between shift‐start time and sleep duration for shifts starting at 03∶00–12∶00 h and with a near linear increase for ones starting between 04∶30 and 09∶00 h of approximately 0.7 h for every 1 h the shift was delayed. The longest sleeps were estimated at ∼8 h before shifts that started at ∼10∶00 h. The shortest sleeps were found for shifts that started before 04∶30 h and were estimated at ∼5 h. Individual differences were estimated with a random-effect standard deviation of 0.51 h, independent of shift‐start time (p =.005). One‐half of the between‐subject variance was explained by subjective health. A one‐step decrease in health was associated with a 26 min increase in sleep length. The results have practical implications for constructing shift schedules. Early morning shifts reduced sleep length substantially and should be mixed with later start hours to avoid the accumulation of sleep dept. Delaying the shift‐start past 10∶00 h had little effect on sleep opportunity; however, delaying shift‐start to between 04∶30 and 9∶00 h had a strong impact on sleep length, with 70% of the extra time used for sleep, suggesting large positive effects for this range of shift‐start times.

Self-reported sleep lengths ≥ 9 hours among Swedish patients with stress-related exhaustion: Associations with depression, quality of sleep and levels of fatigue.

Abstract Background: Insomnia-type sleep disturbances are frequent among patients suffering from stress-related exhaustion disorder. However, clinical observations indicate that a subgroup suffer from sleep lengths frequently exceeding 9 hours, coupled with great daytime sleepiness. Aims: The aim of the present study was to investigate differences in socio-demographic variables, use of medications, sleep parameters, anxiety, depression and fatigue, between individuals with varying sleep lengths, in a sample of 420 Swedish patients (mean age 42 ± 9 years; 77% women) referred to treatment for exhaustion disorder. Patients were allocated to the groups: “never/seldom ≥ 9 hours” (n = 248), “sometimes ≥ 9 hours” (n = 115) and “mostly/always ≥ 9 hours” (n = 57), based on their self-rated frequency of sleep lengths ≥ 9 hours. Methods: The design was cross-sectional and data was collected by means of questionnaires at pre-treatment. Results: Univariate analyses showed that patients in the “mostly/always ≥ 9 hours” group were more often on sick leave, and reported more depression and fatigue, better sleep quality and more daytime sleepiness, than patients in the other groups. Multivariate analyses showed that these patients scored higher on measures of fatigue than the rest of the sample independently of gender, use of antidepressants, sick leave, depression and quality of sleep. Conclusions: Patients suffering from exhaustion disorder and reporting excessive sleep seem to have a generally poorer clinical picture but better quality of sleep than their counterparts with shorter sleep lengths. The mechanisms underlying these differences, together with their prognostic value and implications for treatment remain to be elucidated in future studies.

Railway safety and the train driver information environment

The TRAIN project investigates traffic safety related risks, focusing in particular on the train driver work situation, use of information, and the supporting safety organization. It is an ongoing project funded and managed by the Swedish National Rail Administration and carried out by independent researchers. The project provides a multidisciplinary investigation using task and ergonomic analyses, usability evaluation of the automatic train control (ATC) system, and analyses of stress, mental workload, and work hours. Several methods are used such as interviews, questionnaires, diaries, activity monitoring, and videotapes. Results from parts of the project show that there is a lack of human factors data in accident reports and that drivers report severe problems concerning sleepiness on early morning shifts, problems with maintenance on vehicles, and problems in understanding ATC functions. The problem areas identified show that there is a need for scientific studies of human factors and railway safety as well as safety management programs, including professional human factors competence in the railway industries.

A randomized controlled intervention of workplace-based group cognitive behavioral therapy for insomnia

PurposeSleep disturbance is common in the working population, often associated with work stress, health complaints and impaired work performance. This study evaluated a group intervention at work, based on cognitive behavioral therapy (CBT) for insomnia, and the moderating effects of burnout scores at baseline.MethodsThis is a randomized controlled intervention with a waiting list control group. Participants were employees working at least 75% of full time, reporting self-perceived regular sleep problems. Data were collected at baseline, post-intervention and at a 3-month follow-up through diaries, wrist-actigraphy and questionnaires including the Insomnia Severity Index (ISI) and the Shirom–Melamed Burnout Questionnaire (SMBQ). Fifty-one participants (63% women) completed data collections.ResultsA multilevel mixed model showed no significant differences between groups for sleep over time, while there was a significant effect on insomnia symptoms when excluding participants working shifts (N = 11) from the analysis (p = 0.044). Moreover, a moderating effect of baseline-levels of burnout scores was observed on insomnia symptoms (p = 0.009). A post-hoc analysis showed that individuals in the intervention group with low burnout scores at baseline (SMBQ < 3.75) displayed significantly reduced ISI scores at follow-up, compared to individuals with high burnout scores at baseline (p = 0.005).ConclusionsGroup CBT for insomnia given at the workplace did not reduce sleep problems looking at the group as a whole, while it was indicated that the intervention reduced insomnia in employees with regular daytime work. The results also suggest that workplace-based group CBT may improve sleep in employees with primary insomnia if not concomitant with high burnout scores.