PubMed Health⌕ Search

Biomedical subjects

Göran Kecklund

Publications and source records attributed to Göran Kecklund.

At least 19 recordsLinked to original sources

Recovery after shift work: Relation to coronary risk factors in women.

Shift work increases the risk for developing cardiovascular disease. There is, however, little knowledge of what aspects of shift scheduling that are detrimental and what characteristics promote good health. The aim of the present study was to evaluate whether coronary risk factors deteriorate after a hard work period and whether recovery, in the form of a week off, was sufficient to improve them. A total of 19 women worked an extremely rapidly rotating and clockwise shift schedule at a paper and pulp factory. They underwent two health examinations, one at the end of the work period and one after the week off. In addition, the women were divided into a tolerant and a vulnerable group, depending on their satisfaction with their work hours. Most risk factors did not change, but total cholesterol and low-density lipoprotein (LDL)-cholesterol were lower after the working period than after the week-off. In addition, vulnerable women had higher levels of total cholesterol and a higher ratio of total cholesterol/high-density lipoprotein (HDL) than tolerant ones. In conclusion, the finding that a week-off worsens cholesterol levels was against our hypothesis and suggests further studies on how activities/responsibilities outside the workplace affect shift-working women. It was also shown that susceptible shift workers had worse lipid profiles.

Adult↗

Subjective sleepiness, simulated driving performance and blink duration: examining individual differences.

The present study aimed to provide subject-specific estimates of the relation between subjective sleepiness measured with the Karolinska Sleepiness Scale (KSS) and blink duration (BLINKD) and lane drifting calculated as the standard deviation of the lateral position (SDLAT) in a high-fidelity moving base driving simulator. Five male and five female shift workers were recruited to participate in a 2-h drive (08:00-10:00 hours) after a normal night sleep and after working a night shift. Subjective sleepiness was rated on the KSS in 5-min intervals during the drive, electro-occulogram (EOG) was measured continuously to calculate BLINKD, and SDLAT was collected from the simulator. A mixed model anova showed a significant (P < 0.001) effect of the KSS for both dependent variables. A test for a quadratic trend suggests a curvilinear effect with a steeper increase at high KSS levels for both SDLAT (P < 0.001) and BLINKD (P = 0.003). Large individual differences were observed for the intercept (P < 0.001), suggesting that subjects differed in their overall driving performance and blink duration independent of sleepiness levels. The results have implications for any application that needs prediction at the subject level (e.g. driver fatigue warning systems) as well as for research design and the interpretation of group average data.

Adult↗

Subjective sleepiness and accident risk avoiding the ecological fallacy.

The present study of sleepiness and accident risk in a HI-FI car simulator aimed to provide subject-level relative risks (RR) with 95% confidence intervals (CI) for different levels of subjective sleepiness measured with the Karolinska Sleepiness Scale (KSS), 1 = very alert, 9 = very sleepy, fighting sleep, an effort to staying awake. Five male and five female shift workers, mean age 37 years, participated with a 2-h drive (08:00-10:00 hours) in a dynamic high-fidelity moving base driving simulator, after a night of work and after a night of sleep. Subjective sleepiness was measured with KSS every 5 min and events of incidents (two wheels outside the right lane), accidents (two wheels off the road or four wheels in opposite lane) and crashes (four wheels off the road) were recorded. The probability of an accident was modelled with a Generalized Linear Mixed Model approach to estimate subject-specific effects, rather than group average effects, to avoid the ecological fallacy. The results showed that sleepiness was strongly related to accident risk. An average subject was estimated at 28.2 times (95% CI RR = 10.7-74.1) increased risk at KSS = 8 and at 185 times (95% CI RR = 42-316) at KSS = 9 compared with KSS = 5. There were large individual differences in event propensity that complicates the prediction of absolute accident risk for individual subjects.

Accidents, Traffic↗

Overtime work and its effects on sleep, sleepiness, cortisol and blood pressure in an experimental field study.

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.

Adult↗

Impact of an 84-hour workweek on biomarkers for stress, metabolic processes and diurnal rhythm.

OBJECTIVES: This study examined the degree to which long workhours in combination with an extended workweek (12 hours/7 days) with permanent day shifts (0700-1900), as requested by the workers, influenced biomarkers for stress, metabolic processes, and diurnal rhythm. METHODS: Construction workers (N=50) working 84 hours a week, with alternate weeks off, were compared with construction workers (N=25) having a traditional 40-hour work schedule. The participants were all male and between the ages of 21 to 65 years. Blood samples were obtained in the morning immediately prior to the start of work on workday 1, 5, and 7 to assess cholesterol, cortisol, dehydroepiandrosterone, melatonin, prolactin, testosterone, and uric acid. Psychosocial circumstances were assessed with a questionnaire. RESULTS: The 84-hour group had higher melatonin concentrations and reported higher job-control scores than the 40-hour group. For both groups, the melatonin, cortisol, and cholesterol concentrations were lower on workday 5 than on workday 1. In the 84-hour group, most of the biomarkers were significantly lower in concentrations on workday 7 than on workday 1. Only testosterone showed a significant decrease between workdays 5 and 7. The concentrations of dehydroepiandrosterone and uric acid remained stable across all of the days, as did the melatonin concentrations between workdays 5 and 7. CONCLUSIONS: Working of one's own free will on an 84-hour regimen is not, in the short-term, necessarily more harmful for health than working on a 40-hour regimen with a similar type of heavy worktasks. However, working on an 84-hour schedule beyond the ordinary 40-hour week results in signs of a functional shift in hormonal regulation.

Adult↗

Impaired alertness and performance driving home from the night shift: a driving simulator study.

Driving in the early morning is associated with increased accident risk affecting not only professional drivers but also those who commute to work. The present study used a driving simulator to investigate the effects of driving home from a night shift. Ten shift workers participated after a normal night shift and after a normal night sleep. The results showed that driving home from the night shift was associated with an increased number of incidents (two wheels outside the lane marking, from 2.4 to 7.6 times), decreased time to first accident, increased lateral deviation (from 18 to 43 cm), increased eye closure duration (0.102 to 0.143 s), and increased subjective sleepiness. The results indicate severe postnight shift effects on sleepiness and driving performance.

Accidents, Traffic↗

Comment on short-term variation in subjective sleepiness.

Subjective sleepiness at different times is often measured in studies on sleep loss, night work, or drug effects. However, the context at the time of rating may influence results. The present study examined sleepiness throughout the day at hourly intervals and during controlled activities [reading, writing, walking, social interaction (discussion), etc.] by 10-min. intervals for 3 hr. This was done on a normal working day preceded by a scheduled early rising (to invite sleepiness) for six subjects. Analysis showed a significant U-shaped pattern across the day with peaks in the early morning and late evening. A walk and social interaction were associated with low sleepiness, compared to sedentary and quiet office work. None of this was visible in the hourly ratings. There was also a pronounced afternoon increase in sleepiness, that was not observable with hourly ratings. It was concluded that there are large variations in sleepiness related to time of day and also to context and that sparse sampling of subjective sleepiness may miss much of this variation.

Adolescent↗

The future of work hours--the European view.

In Europe the way work hours are handled varies between different countries. However, there are some issues that dominate the discussion in Europe and seem representative for what is happening. One such is the reduction of working hours--which was attempted in several countries but which now seems to be backfiring--probably related to the competition from countries outside Europe. Another area is compressed work hours--the drive towards maximizing the hours per work day in order to increase the number of days off. The health effects are debated--some find clear positive effects. A third area is company oriented flexible work hours, permitting the employer to make moderate changes in work hours when needed. The health impacts have not been evaluated but the loss of individual influence at work is obvious. In some parts of Europe self-determined work hours have been tried with very positive effects. The EU work hour directive is intended to provide uniformity but permits a counterproductive "opting out", creating problems of imbalance.

Choice Behavior↗

Different levels of work-related stress and the effects on sleep, fatigue and cortisol.

OBJECTIVES: The aim of the study was to relate different levels of work stress to measures of sleep and the diurnal pattern of salivary cortisol and subjective sleepiness. METHODS: Thirty-four white-collar workers participated under two different conditions. One workweek with a relatively high stress level (H) and one with a lower stress level (L) as measured through self-rated stress during workdays. The workers wore activity monitors, filled out a sleep diary, gave saliva samples (for cortisol), and rated their sleepiness and stress during one workday and one free day. RESULTS: During the week with stress the number of workhours increased and total sleep time decreased. Sleepiness showed a significant interaction between weeks and time of day, with particularly high levels towards the evenings of the stress week. Cortisol also showed a significant interaction, with a more flattened pattern, probably due to increased evening levels during the stress week. Stress (restlessness) at bedtime was significantly increased during the stress week. CONCLUSIONS: The results demonstrate that a workweek with a high workload and much stress increases sleepiness and workhours, impairs sleep, and affects the pattern of diurnal cortisol secretion.

Employment↗

Snoring and progression of coronary artery disease: The Stockholm Female Coronary Angiography Study.

STUDY OBJECTIVES: Snoring is associated with a significant increased risk for acute myocardial infarction and stroke. However, our knowledge of mechanisms is still incomplete. The aim of the study was to investigate the influence of snoring in combination with feelings of tiredness on the 3-year progression of atherosclerosis in women with cardiovascular disease. DESIGN: Repeated quantitative coronary angiograms were carried out with an average time interval of 3.25 years. SETTING: Department of Thoracic Radiology at Karolinska Hospital, Stockholm, Sweden. PARTICIPANTS: The study sample comprised 103 women cardiac patients with repeated, valid, and comparable measurement of quantitative coronary angiograms. MEASUREMENTS AND RESULTS: Absolute luminal diameter (in mm) was measured in 10 predefined coronary segments. Mean segment diameter was calculated as the mean of all diameters measured along a given segment. The change over time was calculated by subtracting the first from the second measurement. Snoring and feelings of tiredness were measured by a short version of the Karolinska Sleep Questionnaire. We found that snoring women, after adjusting for age, waist-hip ratio, smoking, event at hospitalization, education, hypertension and alcohol intake, had a statistically significantly larger progression of atherosclerosis than did nonsnoring women (0.18 mm vs 0.07 mm change; P = .0006). CONCLUSION: Snoring contributes to the atherosclerotic process and should be taken into consideration when treating patients with cardiac disease.

Aged↗

Apprehension of the subsequent working day is associated with a low amount of slow wave sleep.

Stress is probably the most frequent cause of short-term insomnia, although it has seldom been documented polysomnographically. A few studies have shown that apprehension is associated with a reduction of slow wave sleep (SWS). The aim of the present study was to examine whether apprehension of the next working day would be related to sleep polysomnography and subjective sleep quality. In this analysis we made use of two different studies (n = 37, mean age: 37 years) that provided inter-individual variation in apprehension of the subsequent working day. The results confirm previous findings that apprehension of a difficult next day is associated with decreased amount of SWS, increased percentage of stage 2 sleep, bedtime state anxiety and subjectively poor sleep. It is concluded that moderate "everyday" stress may disturb physiological restoration as indicated by the reduction of SWS.

Adult↗

Mental fatigue, work and sleep.

OBJECTIVE: The study examined the multivariate relationship between mental fatigue and different work-related (work load, work hours) and background/life style factors, as well as disturbed sleep. METHODS: A total of 5720 healthy employed men and women living in the greater Stockholm area participated in a questionnaire study on cardiovascular risk factors. The data were analysed using a multiple logistic regression analysis with self-rated fatigue as the dependent variable. RESULTS: Fatigue was predicted by disturbed sleep (4.31; 3.50-5.45, high immersion in work (4.17; 2.93-5.94), high work demands (2.39; 1.54-3.69), social support, being a female, being a supervisor and high age. Shift work, work hours (including overtime) and influence at work did not become significant predictors. With control for work demands a high number of work hours was associated with lower fatigue. CONCLUSION: Disturbed sleep is an important predictor of fatigue, apparently stronger than previously well-established predictors such as work load, female gender, lack of exercise, etc.

Adult↗

Individual differences in the diurnal cortisol response to stress.

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 white-collar 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.

Circadian Rhythm↗

Variation in sleepiness during early morning shifts: a mixed model approach to an experimental field study of train drivers.

The present study aimed to experimentally evaluate the effect of early morning shifts on sleep and sleepiness of train drivers during normal working conditions. A total of 17 experienced train drivers were studied during a 4.5 h drive in two directions with a 2.5 h break in between on three different shifts: an early shift that started at 05:49 h (train left at 06:18 h) and ended at 17:41h, a day shift (07:49-19:41 h), and an evening shift (09:49-21:41 h). Retrospective (since the last stop) ratings of mean sleepiness and peak sleepiness (Karolinska Sleepiness Scale--KSS: 1 = very alert, 9= very sleepy, fighting sleep, difficulty staying awake) were assessed at each stop during the drive. The results showed that sleep length was reduced (p <0.001) by 1 h and 2h, respectively, by the early shift compared to the day and evening shifts. The prevalence of severe sleepiness (KSS > or = 7) was high, especially during the early shift when 14 (82%) subjects reported at least one event during the drive. Application of the Generalized Linear Mixed Models (GLMM) to the sleepiness data showed that there was an increased risk for severe sleepiness during the early shift (OR = 4.9) that increased further with the length of the drive between stops (OR = 1.9, 15 min), suggesting an interaction between early morning shift and monotony. The findings have practical implications in risk assessment. Long drives without stops and other monotonous situations should have a higher risk rating for severe sleepiness in shifts with an early start before 06:00 h, compared to shifts that begin 2 h later.

Adult↗

Shift work and mortality.

Despite results linking shift work with ill health, only a few studies have addressed its relation with mortality. The purpose of the present study was to examine the hypothesis that shift work is a predictor of mortality. The study involved a sample of 22,411 individuals of the Swedish population. Data were obtained through annual phone interviews done between 1979 and 2000. Cox regression analysis was used to assess the association between shift work/day work as the independent variable and death/survival during the subsequent years as the dependent variable. Separate analyses were carried out for female and male white- and blue-collar workers, respectively. The results were adjusted for age, stress, physical work load, disease at the outset of the study, and smoking. Mortality was significantly increased for female white-collar workers, with a Hazard Ratio of 2.61 and a 95% confidence interval of 1.26-5.41. No other significant effects were found. It is concluded that blue-collar shift work is not related to mortality, but that risk of death is increased for women white-collar shift workers compared to women white-collar day workers.

Adolescent↗

Tolerance to shift work-how does it relate to sleep and wakefulness?

OBJECTIVES: There is limited knowledge as to why some individuals tolerate shift work and others do not. As a consequence of their intolerance, many individuals develop dissatisfaction with their shift schedule. To evaluate if dissatisfaction with one's shift system was related to alterations of the daily pattern of sleep and sleepiness, we followed two groups of shift workers that were either highly satisfied or dissatisfied with their shift schedule, during an entire shift cycle. METHODS: Thirty-six male and 20 female shift workers were selected according to their satisfaction with their shift schedule. The shift cycle included seven work periods ("triads" of shifts; night shift-afternoon shift-morning shift), with only 8-9 hours off (quick returns) between shifts, but followed by a day off. RESULTS: Sleep length was reduced after night shifts (4.8 h) and afternoon shifts (5.4 h). Sleepiness was increased during all shifts, particularly night shifts. Sleepiness did not accumulate across the shift cycle even though sleepiness was slightly increased directly after the last triad of shifts. There were few significant gender differences. Dissatisfied shift workers reached much higher levels of sleepiness and reported less sufficient sleep, but not objectively poorer or shorter sleep. Amongst dissatisfied workers, this resulted in an increase of sleepiness problems across shifts within the triad of shifts. Dissatisfied workers also had more performance lapses at the end of the night shift. CONCLUSIONS: Satisfaction with the shift schedule seems to reflect how well the shift workers were coping with the schedule. It is suggested that the increase of sleep/wake problems within the work period for the dissatisfied shift workers is related to increased sensitivity to curtailed and displaced sleep.

Adult↗

Hormonal changes in satisfied and dissatisfied shift workers across a shift cycle.

Although the literature claims that shift work is harmful, it overlooks the fact that that many shift workers are satisfied and stay healthy. There is little knowledge of the biological mechanisms mediating the differences in susceptibility. The present study compared satisfied and dissatisfied shift workers with respect to major anabolic and catabolic hormones. Forty-two male shift workers, with an extremely rapidly rotating shift schedule, were divided into two groups according to their ratings of satisfaction with their work hours. Morning blood samples were taken during the first and last morning shift in the shift cycle. Serum was analyzed with respect to testosterone, cortisol, and prolactin. Dissatisfied shift workers had lower morning testosterone than satisfied ones, but they did not significantly differ with respect to cortisol or prolactin. Low testosterone levels were, in addition, associated with a greater sleep need, disturbed sleep/wakefulness, and an increased need for recovery after the work period, the latter being the best predictor of testosterone levels. The only change across the shift cycle concerned a significant decrease of morning cortisol at the end of the shift cycle. High morning cortisol was related to having a morning personality and fewer sleep problems before the morning shift. Dissatisfaction with the shift system seems related to lower testosterone levels, which in turn are related to disturbed sleep/wakefulness and increased need for sleep and recovery. Furthermore, morning cortisol was reduced across a shift cycle. It is suggested that reduced testosterone levels may be part of a mechanism of shift work maladjustment.

Adult↗

Poor sleep increases the prospective risk for recurrent events in middle-aged women with coronary disease. The Stockholm Female Coronary Risk Study.

OBJECTIVE: We investigated the prognostic impact of sleep complaints in women with CHD and also examined whether the association between sleep problems and cardiac events could be explained by depression. METHODS: All women patients, aged 65 or under who were admitted with an acute coronary syndrome between 1991 and 1994 in Stockholm, were followed for 5 years for recurrent coronary events. Sleep complaints and depression were measured at baseline using standardized questionnaires. Quality of sleep, restorative function of sleep, and snoring were assessed by the Karolinska Sleep Questionnaire (KSQ), and depressive symptoms by a questionnaire developed by Pearlin. RESULTS: Poor sleep quality was associated with recurrent cardiac events. After multivariate adjustment for age, and standard risk factors, the hazard ratio (HR) for women with poor as compared with good sleep quality was 2.5 (95% CI: 1.2-5.2). Controlling for depression did not change this result substantial. Not waking up well-rested yielded a similarly increased risk (HR = 2.4; 95% CI: 1.2-4.6). Women with both poor sleep quality and depression had a worse prognosis than women free from these complaints (HR = 2.6; 95% CI: 1.0-6.4). Heavy snoring was not related to prognosis. CONCLUSIONS: Our results indicate that poor sleep and sleep without a restorative function are associated with poor prognosis in female coronary patients. This association is not explained by depressive symptoms or by standard coronary risk factors.

Aged↗