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- Theorell-Haglöw, Jenny, 1976-
(author)
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Sleep and Sleep-disordered Breathing in Women : Associations with Daytime Symptoms and Metabolism
- 2009
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Doctoral thesis (other academic/artistic)abstract
- Obstructive sleep apnea (OSA) is characterized by snoring, apneas and excessive daytime sleepiness (EDS). Although commonly present in OSA, factors relating to daytime sleepiness are not fully elucidated. OSA is associated with obesity and with cardiovascular disease, type 2 diabetes mellitus and the metabolic syndrome. In this population-based study 7,051 women answered a questionnaire on sleep and health. Psychological distress, insomnia and somatic disease were the factors most strongly related to both EDS and fatigue independent of other factors. Snoring was independently associated with both EDS and fatigue, but the associations were relatively weak. In addition, 400 of the women underwent polysomnography and an oral glucose tolerance test. OSA was associated with changes in glucose metabolism independently of confounders such as central obesity. Moreover, low minimal saturation was independently associated with reduced insulin sensitivity. In women sleeping <6-7 hours there was a substantial increase in waist circumference and short sleep duration remained associated with central obesity, even after adjusting for body mass index (BMI). The most pronounced negative influence of short sleep duration and also reduced duration of slow-wave sleep (SWS) or rapid eye movement (REM) sleep was seen in women <50 years. All measures of OSA were related to the metabolic syndrome after adjustments. In addition, the relationship remained after adjusting for central or general obesity. Hypoxia was independently associated with hypertriglyceridemia, even after adjusting for BMI. In conclusion, OSA may have significant impact on insulin sensitivity and metabolism in women, and the relationship could, to some extent, be mediated through hypoxia. Moreover, reduced sleep duration and loss of SWS and REM sleep may influence central obesity; a strong risk factor for OSA. Daytime sleepiness was most strongly related to psychological distress, insomnia and somatic disease although snoring was also a risk factor. This finding indicates that sleep apnea is only one factor contributing to daytime sleepiness in women.
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| 2. |
- Axelsson, John, 1969-
(author)
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Long shifts, short rests and vulnerability to shift work
- 2005
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Doctoral thesis (other academic/artistic)abstract
- At the same time as many urban economies are developing into 24-hour societies it is becoming increasingly popular amongst shift workers to compress their working hours. This is done by working longer shifts (>8h) and/or restricting free time (<16h) in between shifts – the main reasons are to gain longer bouts of free time and extra free weekends. However, there is a limited knowledge of the effects of such arrangements on sleep and wakefulness. Thus, the main purposes of the present thesis were to evaluate the effects of long working hours (in the form of 12h shifts) and short recovery periods. Another aim was to evaluate possible mechanisms that could suggest why some individuals develop problems with shift work while others do not.We used a combination of methods - sleep diaries, wake diaries, blood samples and objective measures of sleep and cognitive performance - across whole or large parts of shift schedules to evaluate acute effects of particularly demanding working periods, as well as the total effects of a shift cycle. Study I evaluated the effect of changing from an 8h- to a 12h-shift system. Study II evaluated the effects of long shifts in a shift schedule with both 8h- and 12h-shifts. Study III evaluated the effects of several consecutive short recovery periods (8-9h of recovery) and whether satisfaction with ones’ work hours was associated to problems with sleep and sleepiness. Study IV evaluated whether endocrinological markers of catabolic (cortisol) and anabolic (testosterone) activity changed across a shift sequence and whether satisfaction were related to them. Study V was a laboratory simulation of the effects of a short recovery period (4h of sleep) and whether a short nap could counteract any detrimental effects.There was no convincing evidence for 12h shifts inducing more problems with sleep and sleepiness than 8h shifts. With regard to recovery time between shifts, the shortest recovery times (only 8h) seriously shortened sleep duration and increased sleepiness, while 12h of recovery (between two consecutive 12h shifts) was judged as having no or limited effects on acute measures. The problems with the shortest recovery periods were worse in a schedule with several consecutive shifts and less pronounced in a schedule with few consecutive shifts. With regard to individual differences, it was found that subjects being dissatisfied with their working hours were vulnerable to short recovery periods, which was evident by less sufficient sleep and an accumulation of sleepiness across work periods with limited recovery time. Interestingly, these problems disappeared when they were allowed to recover after the work period. In addition, dissatisfied male shift workers had lower testosterone levels at the end of work periods, indicating disturbed anabolic activity. The simulated quick return supported that curtailed sleep affected sleepiness and performance and that a short nap could counteract these effects temporarily.It is concluded that long shifts (up to 12h) may be acceptable, whereas short recovery time (8h or less) is not. Most of the problems with short recovery periods were related to short sleep and sleepiness, and there is, clearly, a subgroup of workers that suffer more from this than others. It is argued that insufficient sleep and low testosterone levels (in males) might be key factors for developing shift intolerance, mainly by reducing the capacity to recover from shift work.
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| 3. |
- Dahlgren, Anna
(author)
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Work stress and overtime work - effects on cortisol, sleep, sleepiness and health
- 2006
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Doctoral thesis (other academic/artistic)abstract
- In Sweden the National Bureau of Statistics has reported an increase in stress-related disorders and sleep problems since the mid-1990’s. They also report that the number of hours of overtime worked has increased. Previous research on work-related stress and overtime work has demonstrated associations with altered physiological arousal, increased risk for stress related diseases, shorter sleep, greater fatigue and impaired performance. However, there is a lack of knowledge on the effects within individuals. The general aim of the thesis was to investigate the effect of overtime work and increased work stress on sleep, the diurnal pattern of cortisol, sleepiness and subjective stress in a within-subject design. In addition, it examined individual differences in the diurnal cortisol response to stress.We used a combination of methods – questionnaires, sleep and wake diaries, objective measures of sleep, stress hormones (salivary cortisol) and ambulatory measures of heart rate and blood pressure. Studies followed office workers during two different conditions of (I) high/low work stress and (II) overtime work respectively. The individual differences in the cortisol response to stress from study I prompted study III. In this study we examined two groups that showed different cortisol responses to stress.In conclusion, the results (I) demonstrated that a week with higher workload and stress affects physiological stress markers such as cortisol, and is associated with increased sleepiness and problems of unwinding at bedtime, shorter sleep duration and longer work hours. Furthermore (II) overtime work, under conditions of relatively low workload, was shown to be associated with modest effects on physiological markers of arousal. More pronounced effects were found on sleep and fatigue, with greater problems during overtime work. Study III indicated that individual differences in cortisol response to stress maybe related to fatigue and exhaustion.
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| 4. |
- D'Onofrio, Paolo, et al.
(author)
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The Polysomnographical Meaning of Changed Sleep Quality-A Study of Treatment with Reduced Time in Bed
- 2023
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In: Brain Sciences. - : MDPI. - 2076-3425. ; 13:10
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Journal article (peer-reviewed)abstract
- Background: Reports of poor sleep are widespread, but their link with objective sleep (polysomnography-PSG) is weak in cross-sectional studies. In contrast, the purpose of this study was to investigate the association between changes in subjective and objective sleep variables using data from a study of the reduction in time in bed (TIB). Methods: One sleep recording was carried out at baseline and one at treatment week 5 (end of treatment) (N = 34). Results: The Karolinska Sleep Quality Index improved and was correlated with improvement in sleep efficiency (r = 0.41, p < 0.05) and reduction in TIB (r = -0.47, p < 0.01) and sleep latency (r = 0.36, p < 0.05). The restorative sleep index showed similar results. Improvements in the insomnia severity index (ISI) essentially lacked correlations with changes in the PSG variables. It was suggested that the latter may be due to the ISI representing a week of subjective sleep experience, of which a single PSG night may not be representative. Conclusions: It was concluded that changes in the subjective ratings of sleep are relatively well associated with changes in the PSG-based sleep continuity variables when both describe the same sleep.
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| 5. |
- Ekstedt, Mirjam, Professor, et al.
(author)
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Planerad vila förebygger överträning
- 2010
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In: Svensk idrottsmedicin. - : Svensk Idrottsmedicinsk Förening, SIMF. - 1103-7652. ; :1, s. 14-17
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Journal article (pop. science, debate, etc.)abstract
- Utvecklingen från naturlig trötthet till utmattning följer ungefär samma förlopp vid mentalöveransträngning som vid sjukdom eller fysisk överbelastning. Genom att aktivt prioritera ochplanera in tid för vila och återhämtning förebygger man överträning och utmattning.
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| 6. |
- Rosén, Ann, et al.
(author)
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A comparison of sleep restriction and sleep compression on objective measures of sleep : A sub-sample from a large randomised controlled trial
- 2023
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In: Journal of Sleep Research. - : John Wiley & Sons. - 0962-1105 .- 1365-2869. ; 32:4
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Journal article (peer-reviewed)abstract
- Sleep restriction therapy is a central component of cognitive behavioural therapy for insomnia, but can lead to excessive sleepiness, which may impede treatment adherence. Sleep compression therapy has been suggested as a possibly gentler alternative. The aim of this study was to compare the effects of sleep restriction therapy and sleep compression therapy on objective measures of sleep, with a focus on magnitude and timing of effects. From a larger study of participants with insomnia, a sub-sample of 36 underwent polysomnographic recordings, before being randomised to either sleep restriction (n = 19) or sleep compression (n = 17) and receiving online treatment for 10 weeks. Assessments with polysomnography were also carried out after 2, 5, and 10 weeks of treatment. Data were analysed with multilevel linear mixed effect modelling. As per treatment instructions, participants in sleep restriction initially spent shorter time in bed compared with sleep compression. Participants in sleep restriction also showed an initial decrease of total sleep time, which was not seen in the sleep compression group. Both treatments led to improvements in sleep continuity variables, with a tendency for the improvements to come earlier during treatment in sleep restriction. No substantial differences were found between the two treatments 10 weeks after the treatment start. The results indicate that homeostatic sleep pressure may not be as important as a mechanism in sleep compression therapy as in sleep restriction therapy, and an investigation of other mechanisms is needed. In conclusion, the treatments led to similar changes in objective sleep at a somewhat different pace, and possibly through different mechanisms.
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