Original ArticleSleep and sadness: exploring the relation among sleep, cognitive control, and depressive symptoms in young adults
Introduction
Sleep disturbance is a common feature of depression and as such represents one of nine symptoms of a depressive episode [1]. Some estimates suggest that up to 90% of individuals with major depression also are diagnosed with insomnia [2]. There also is empirical evidence that depression is associated with nonclinical sleep disturbances (e.g., reduced total sleep time, increased sleep-onset latency) [3]. Importantly, recent research shows that sleep disturbance may not only be a symptom of depression but may in fact precede the disorder. For example, Chen et al. [4] found that daughters of depressed mothers reported poorer sleep quality than girls at low familial risk for depression. In addition, sleep restriction has been shown to increase depressive symptoms among otherwise healthy individuals [5]. In sum, sleep difficulties characterize depressive episodes and may serve as a phenotype of risk for the disorder. Therefore, our study sought to identify the underlying mechanisms by which sleep difficulties may contribute to depression symptomatology.
It is possible that sleep disturbance influences depressive symptoms through its impact on cognition. Indeed, sleep difficulties and depression have been independently linked to deficits in cognitive control. For example, sleep deficits are associated with poor performance on tasks measuring mental flexibility [6], working memory [7], attentional set shifting [8], and inhibition [9]. Depression also has been linked to cognitive control deficits, particularly during emotional information processing. Depressed individuals exhibit difficulties inhibiting the processing of negative material [10], [11], disengaging attention from negative material [12] and removing negative material from working memory [13]. Given these results, our study examined if sleep difficulties are associated with reduced cognitive control over emotional stimuli and if these reductions are linked to increases in depressive symptoms.
Notably, much of the work on sleep and depression has relied on self-report measures. However, it is possible that negative reporting biases which often precede and characterize the disorder may account for observed group differences. Therefore, any study of sleep and depressive symptoms should consider including both self-report and objective measures of sleep disturbance. Actigraphy represents one method to objectively examine sleep in a naturalistic setting [14]. Actigraph devices use an accelerometer to measure movement across time and researchers can use movement data to infer periods of sleep and wakefulness. In contrast to other sleep methodologies (e.g., sleep deprivation, polysomnography [PSG]), actigraphy allows researchers to objectively measure naturalistic sleep outside the laboratory. In addition to measuring traditional sleep measures such as total sleep time, actigraphy also can provide measures of circadian rhythms [15]. Especially in the cognition literature, there is evidence that circadian rhythm measures account for outcomes above and beyond those accounted for by average sleep duration or changes in sleep duration [16], [17], [18]. Additionally, although some individuals have conceptualized depression as a disorder of disrupted circadian rhythms [19], research on the relation between sleep–wake cycles and depression is lacking. Therefore, our study utilized both subjective and objective measures of sleep difficulties and circadian rhythms to examine their relation to cognitive control and depressive symptoms.
Our study recruited a sample of undergraduate students to identify factors that may underlie the relation between sleep difficulties and depressive symptoms. In doing so, we first examined the relation between sleep and depressive symptoms. In line with previous findings, we hypothesized that poorer sleep quality and reduced sleep duration would predict increases in depressive symptoms. Second, because previous research has linked both sleep and depression to deficits in cognitive control, we hypothesized that cognitive control over negative stimuli would mediate the relation between sleep quality and change in depressive symptoms. As a final exploratory objective of the study, we explored if variation in a single nucleotide polymorphism (SNP) in the circadian locomotor output cycles kaput gene, CLOCK, related to our primary variables of interest (i.e., sleep, cognitive control, depressive symptoms). The CLOCK SNP, rs11932595, was chosen because it has previously been linked to variation in daily sleep time [20].
Section snippets
Participants
Researchers posted flyers at The University of Texas at Austin advertising a study on sleep and cognition. Current undergraduate students at The University of Texas at Austin who were at least 18 years of age were eligible to participate in the study. Individuals who responded to the flyers via e-mail received a written description of the study. Individuals who remained interested in the study and who met inclusion criteria were scheduled for the first laboratory session.
Fifty-two individuals
Descriptive statistics
Means, SDs, and correlations among the relevant variables are presented in Table 1. We first examined the relation between sleep and depressive symptoms. Depressive symptoms and self-reported sleep difficulties were moderately correlated. Total sleep was moderately associated with depression symptoms at time two but fell short of statistical significance (P = .08). Sleep stability (IS), fragmentation (IV), and variability (SD) were weakly associated with depressive symptoms at both time points.
Discussion
Our study explored the relation among sleep, cognitive control, and depressive symptoms in a two-session study with a sample of undergraduate students. First, we found that self-reported sleep quality between the two laboratory sessions predicted depressive symptoms at time 2 after controlling for depressive symptoms at time 1. Specifically, poorer sleep quality was associated with greater increases in depressive symptoms. This finding supports those of Chen et al. [4], suggesting that 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: http://dx.doi.org/10.1016/j.sleep.2013.10.006.
Acknowledgments
The authors would like to thank the Chief of the Army—Grant to West Point Network Science Center, subcontracted to The University of Texas at Austin, for funding this study.
References (36)
- et al.
The effects of sleep deprivation on symptoms of psychopathology in healthy adults
Sleep Med
(2007) - et al.
Dissociation of cortical regions modulated by both working memory load and sleep deprivation and by sleep deprivation alone
Neuroimage
(2005) - et al.
Effects of sleep restriction on cognition in women
Biol Psychol
(2008) - et al.
Deficient inhibition of emotional information in depression
J Affect Dis
(2006) Performance and sleepiness following moderate sleep disruption and slow wave sleep deprivation
Physiol Behav
(1986)- et al.
CLOCK gene variants associate with sleep duration in two independent populations
Biol Psychiatry
(2010) - et al.
The Pittsburgh sleep quality index: a new instrument for psychiatric practice and research
Psychiatry Res
(1989) - et al.
The chi square periodogram: its utility for analysis of circadian rhythms
J Theor Biol
(1978) - et al.
Alterations in the circadian rest–activity rhythm in aging and Alzheimer’s disease
Biol Psychiatry
(1990) - et al.
Insomnia as a predictor of depression: a meta-analytic evaluation of longitudinal epidemiological studies
J Affect Dis
(2011)
5th ed.
Sleep and depression
J Clin Psychiatry
Insomnia in psychiatric disorders
Reduced sleep quality in healthy girls at risk for depression
J Sleep Res
The cumulative cost of additional wakefulness: dose–response effects on neurobehvioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation
Sleep
Self-reported sleep quality predicts poor cognitive performance in healthy older adults
J Gerontol B Psychol Sci Soc Sci
Attentional bias in dysphoria: the role of inhibitory processes
Cogn Emotion
Mood-congruent attentional bias in dysphoria: maintained attention to and impaired disengagement from negative information
Emotion
Cited by (61)
Circadian clock genes and circadian phenotypes in patients with myocardial infarction
2019, Advances in Medical SciencesCitation Excerpt :In the present study, rs11932595 was associated with daytime sleepiness in MI patients. Other research by Vanderlind et al. found that rs11932595 is associated with sleep quality [47]. Short sleep time harms health and is associated with increased mortality, coronary artery disease, type 2 diabetes mellitus, obesity, and hypertension.
Love is a physiological motivation (like hunger, thirst, sleep or sex)
2019, Medical HypothesesSleep regularity is associated with sleep-wake and circadian timing, and mediates daytime function in Delayed Sleep-Wake Phase Disorder
2019, Sleep MedicineCitation Excerpt :For example, previous research has demonstrated that variability of sleep duration in particular, rather than timing, is related to depression [60]. Several studies investigating variability in sleep duration found that night-to-night variability in both actigraphically measured [24,61] and self-report [24] sleep duration was significantly associated with increased depressive symptom severity. Similar findings were reported for insomnia patients, where increased variability of sleep duration was significantly associated with increased depressive symptoms [62].