Original ArticlePredicting sleep quality from stress and prior sleep – A study of day-to-day covariation across six weeks
Introduction
Stress is seen as the primary cause of persistent psychophysiological (or primary) insomnia [1]. In the International classification of sleep disorders (ICSD2) [2] “adjustment insomnia” represents the effects of acute stress, whereas “primary insomnia” represents the long-term consequences of mainly adjustment insomnia.
Most research on stress and sleep has been experimental in nature and has not dealt with stress in daily life [3], except for some cross-sectional epidemiological studies [4], [5], [6], [7], [8], [9]. All indicate a clear negative correlation between stress and sleep quality.
While informative, cross-sectional studies have problems with causal links. The first prospective study of work stress and sleep seems to be the one by Ribet et al. [6] who studied more than 21,000 subjects in France using a sleep disturbance index. Shift work, a long working week, exposure to vibrations, and “having to hurry” appeared to be the main risk factors, controlling for age and gender. Another prospective self-report study across three points in time showed a relation between work demands and sleep quality [10]. Similarly, Linton et al. related “negative psychosocial work conditions” to insomnia, with an Odds Ratio across five years of 2.15 [11]. Jansson and Linton [12] controlled for initial insomnia in a similar design and found that high work demands at the outset predicted impaired sleep one year later. Using another approach, Mezick et al. showed that prior stressful life events were related to a later increase in daily variability of sleep [13]. Hall et al. [14] demonstrated that financial strain was related to poorer subjective sleep quality and to reduced sleep efficiency.
An alternative to prospective epidemiological studies across a period of years is to focus on the day-to-day variation in stress in daily life and its corresponding day-to-day variation in sleep quality. Does a stressful day in daily life lead to a reduced sleep quality that night, and would such a relation hold across a number of days in daily life? In one study in which a low and high stress day were selected out of five measures the results showed reports of reduced sleep quality as well as reduced sleep efficiency and increased latency to Stage 3 sleep after a high stress day [15].
While occasional days with heavy stress might affect sleep, one may wonder whether the, presumably, modest variation in stress in daily life during a longer period of time led to disturbed sleep. If stress would show a coupling to subsequent sleep on a day-to-day basis, this would add credibility to earlier large but coarse-grained studies on this issue. To the best of our knowledge only one study of the relation between daily stress and subsequent sleep has been carried out. It was based on longitudinal, intraindividual correlations between stress and sleep ratings mainly in insomnia patients [1]. It showed a rather weak, but significant, correlation indicating that increased stress was followed by reduced sleep quality. Today, a more timely approach would be to use multilevel modeling, which would permit both between and within-groups analyses and estimates of the shape of the relation [16]. Such an approach has been used for investigating the daily variation of sleep on the daily variation of mood across two weeks, finding that reduced sleep affects mood the subsequent day [17].
The aim of the present study was to investigate how the daily variation in stress during the day/evening would be related to the daily variation in reported sleep quality the next morning over a period of 42 days in healthy individuals. The hypothesis was that day/evening stress would result in reports of poor sleep the next morning. The design also included other factors that might affect sleep and confound the relation between stress and sleep, for example alcohol intake in the evening, time of turning off the lights to sleep (lights out), self-rated health (SRH), sleep quality the night before the day of rated stress, a day off, etc. In addition, background factors such as age, gender, depression, and anxiety were used as possible modifiers.
Section snippets
Subjects and procedures
A total of 50 subjects participated. All were recruited through advertisements and contacts and thus constituted a convenience sample. Advertisements were displayed at the Karolinska Institute and employees were encouraged to ask friends and family to participate. Twelve percent were excluded because of insomnia, heavy snoring, or depression. The participants received an economic compensation of approximately $180. The ethical committee of the Karolinska Institute approved the study. All
Results
Table 1 presents the mean and standard deviation for the included variables. See methods for data on health, gender, etc.
Table 2 presents the main results of the mixed model analyses. Coffee consumption (mean: 2.35 ± 1.81 cups/day), alcohol intake, and prior time of awakening did not show a significant contribution in the univariate analyses (the fixed coefficient ± se for coffee was: −0.025 ± 0.015) and were not included in the multivariate analysis. The same was true for the background factors age,
Discussion
The results indicate that feelings of stress/worries at bedtime significantly predicted worse subjective sleep quality on a day-to-day basis across 42 days. The results extend previous longitudinal [1], cross-sectional [4], [5], [6], [7], [8], and prospective [6], [11], [12], [15] studies linking stress with sleep quality. In the present work the added value concerns the stress-sleep link in the day-to-day variation in stress and sleep across a number of days (42). Thus, the stress–sleep
Conflict of interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: doi:10.1016/j.sleep.2011.12.013.
References (35)
- et al.
Work load and work hours in relation to disturbed sleep and fatigue in a large representative sample
J Psychosom Res
(2002) - et al.
Intra-individual variability in sleep duration and fragmentation: associations with stress
Psychoneuroendocrinology
(2009) - et al.
Impaired sleep after bedtime stress and worries
Biol Psychol
(2007) - et al.
Cognitive approaches to insomnia
Clin Psychol Rev
(2005) - et al.
An open trial of cognitive therapy for chronic insomnia
Behav Res Ther
(2007) Epidemiology of insomnia: what we know and what we still need to learn
Sleep Medicine Reviews.
(2002)- et al.
Role of stress, arousal, and coping skills in primary insomnia
Psychosom Med
(2003) - AASM. ICSD – International classification of sleep disorders, revised: diagnostic and coding manual. Chicago, Illinois:...
- et al.
The effect of psychosocial stress on sleep: a review of polysomnographic evidence
Behav Sleep Med
(2007) - et al.
Self-evaluations of factors promoting and disturbing sleep: an epidemiological survey in Finland
Social Sci Med
(1982)
Characteristics of insomnia in the United States: results of the 1991 National Sleep Foundation survey. I
Sleep
Age, working conditions, and sleep disorders: a longitudinal analysis in the French cohort E.S.T.E.V.
Sleep
Relationships of occupational stress to insomnia and short sleep in japanese workers
Sleep
Job stress and poor sleep quality: data from an American sample of full-time workers
Social Sci Med
A hard day’s night: a longitudinal study on the relationships among job demands and job control, sleep quality and fatigue
J Sleep Res
Does work stress predict insomnia? A prospective study
Br J Health Psychol
Psychosocial work stressors in the development and maintenance of insomnia: a prospective study
J Occup Health Psychol
Cited by (132)
Sleep and daytime functioning in autistic teenagers: A psychological network approach
2024, Research in Autism Spectrum DisordersSleep and allostatic load: A systematic review and meta-analysis
2022, Sleep Medicine ReviewsCitation Excerpt :First, sleep is a biological process that depends on allostatic and homeostatic processes [17,18]. Second, stress is central to the AL model, and sleep problems are well-known behavioral consequences of stress [19,20]. Third, sleep difficulties may themselves represent a stressor, not only psychologically but also physiologically, as sleep is an important mechanism driving hormone release, cardiovascular activity, and metabolism [13,21].
Sleep, stress and aggression: Meta-analyses investigating associations and causality
2022, Neuroscience and Biobehavioral ReviewsEffects of stress on sleep quality: multiple mediating effects of rumination and social anxiety
2024, Psicologia: Reflexao e Critica