Depression as a confounding variable in the estimation of habitual sleep time

Objective and subjective sleep in patients with non-seasonal major depressive disorder and eveningness - Results from a randomized controlled trial of bright light therapy

STUDY OBJECTIVES

This study examines the (dis)agreement between objective and subjective sleep and their prospective changes in a randomized controlled trial of bright light therapy (BLT) in patients with major depressive disorder (MDD) and eveningness.

METHODS

A total of 93 adults were randomized to receive either 30-min daily of 10,000 lux BLT or 50lux placebo dim red light therapy (DRL group) for a total of 5 weeks. Actigraphic data were collected at the baseline and during the last week of treatment. (Dis)Concordance of diary and actigraphic sleep parameters were assessed by partial correlations and Bland-Altman plots, and the associations between these discrepancies to depression severity was assessed by linear regression models. Changes of sleep parameters were assessed by linear mixed models.

RESULTS

Significant correlations were found between subjective sleep timings and chronotype to actigraphic parameters. Discrepancies between diary- and actigraphic-measures were observed, and patients with more severe depressive symptoms were associated with a greater under-estimation of total sleep time (TST). A greater advance in the diary-based time to fall sleep and rise time were achieved in the BLT group as compared to the DRL group, while diary-based wake after sleep onset (WASO), TST and sleep efficiency (SE) comparably improved with time in both groups. There was no significant difference between the two groups in the actigraphic parameters after treatment.

CONCLUSIONS

In this study, we found that depression severity influenced subjective report of sleep. BLT led to a greater advance in subjective sleep timings when compared to the placebo group.

Negative and positive sleep state misperception in patients with insomnia: factors associated with sleep perception

STUDY OBJECTIVES

In the present study, factors associated with sleep perception were identified by comparing clinical characteristics and polysomnographic variables between insomnia patients with negative and positive sleep state misperception (NSSM and PSSM, respectively).

METHODS

Subjective and objective sleep measures were retrospectively collected, including the Pittsburgh Sleep Quality Index (PSQI), Beck Depression Inventory (BDI), and a questionnaire on "morning feeling" after nocturnal polysomnography (PSG) in 150 patients with insomnia. Based on the misperception index (MI), participants were classified into NSSM (MI > 0, n = 115) and PSSM (MI < 0, n = 35) groups.

RESULTS

The PSSM group had more N3 sleep on nocturnal PSG than the NSSM group (p=0.002). The NSSM group showed a higher PSQI score (p<0.001), longer subjective sleep onset latency (SOL) (p=0.001), and a greater SOL discrepancy (p=0.001). Subjective feelings of tiredness and morning awakenings in the morning were higher in the NSSM group (p=0.029 and p=0.038). The MI negatively correlated with a proportion of N3 sleep (p=0.005) and positively correlated with PSQI (p<0.001), morning awakenings (p=0.01), subjective SOL (p<0.001), and SOL discrepancy (p<0.001) in insomnia patients. Multiple regression analysis showed that N3 sleep, PSQI, and morning awakenings were significantly associated with MI in insomnia patients.

CONCLUSIONS

The proportion of slow-wave sleep and subjective measures may be associated with perception of sleep in insomnia patients. Objective and subjective characteristics of insomnia patients should be carefully evaluated and managed because they may influence the perception of sleep.

Sleep-wake misperception. A comprehensive analysis of a large sleep lab cohort

OBJECTIVES

Sleep-wake misperception has mainly been reported in insomnia patients. Conversely, the present study aimed to assess the prevalence and correlates of sleep-wake misperception in a large cohort of patients with various sleep-wake disorders, all diagnosed along the third version of the International Classification of Sleep Disorders.

METHODS

We retrospectively included 2738 patients examined by polysomnography, who in addition estimated upon awakening their total sleep time, sleep onset latency and Wake after sleep onset (WASO). We computed subjective-objective mismatch by the formula (subjective - objective value)/objective value ×100; negative and positive values indicated under- and overestimation, respectively.

RESULTS

In the entire sample, the magnitude of under- and overestimation of total sleep time was similar, but varied significantly between diagnostic groups, with insomnia and insufficient sleep syndrome showing the most pronounced underestimation and REM parasomnia and circadian rhythm disorders showing the most pronounced overestimation of total sleep time. In all diagnostic categories, a majority tended to overestimate their sleep onset latency and to underestimate the amount of WASO. Younger age was independently correlated with underestimation of total sleep time and WASO, and with overestimation of sleep onset latency. Overestimation of sleep onset latency independently correlated to an increased latency to N3 sleep stage on polysomnography.

CONCLUSIONS

While sleep-wake misperception is highly prevalent in all sleep-wake disorders, significant differences exist in magnitude of under- and overestimation between distinct diagnostic groups.

The association between depressive symptoms and self-reported sleep difficulties among college students: Truth or reporting bias?

The strong association between self-reported sleep difficulties and depressive symptoms is well documented. However, individuals who suffer from depressive symptoms could potentially interpret the values attached to a subjective scale differently from others, making comparisons of sleep difficulties across individuals with different depressive symptoms problematic. The objective of this study is to determine the existence and magnitude of reporting heterogeneity in subjective assessment of sleep difficulties by those who have depressive symptoms. We implement an online survey using Visual Analogue Scales and anchoring vignettes to study the comparability of subjective assessments of sleep difficulties among college students in Switzerland (N = 1, 813). Using multivariate linear regressions and double-index models, our analysis shows that reporting heterogeneity plays only a marginal role in moderating the association between sleep difficulties and depression, irrespective of the severity of the depressive symptoms of the individuals. This suggests that unadjusted comparisons of self-reported sleep difficulties between college students are meaningful, even among individuals with depressive symptoms.

Poor Sleep Quality Associates With Decreased Functional and Structural Brain Connectivity in Normative Aging: A MRI Multimodal Approach

Sleep is a ubiquitous phenomenon, essential to the organism homeostasis. Notwithstanding, there has been an increasing concern with its disruption, not only within the context of pathological conditions, such as neurologic and psychiatric diseases, but also in health. In fact, sleep complaints are becoming particularly common, especially in middle-aged and older adults, which may suggest an underlying susceptibility to sleep quality loss and/or its consequences. Thus, a whole-brain modeling approach to study the shifts in the system can cast broader light on sleep quality mechanisms and its associated morbidities. Following this line, we sought to determine the association between the standard self-reported measure of sleep quality, the Pittsburgh Sleep Quality Index (PSQI) and brain correlates in a normative aging cohort. To this purpose, 86 participants (age range 52–87 years) provided information regarding sociodemographic parameters, subjective sleep quality and associated psychological variables. A multimodal magnetic resonance imaging (MRI) approach was used, with whole-brain functional and structural connectomes being derived from resting-state functional connectivity (FC) and probabilistic white matter tractography (structural connectivity, SC). Brain regional volumes and white matter properties associations were also explored. Results show that poor sleep quality was associated with a decrease in FC and SC of distinct networks, overlapping in right superior temporal pole, left middle temporal and left inferior occipital regions. Age displayed important associations with volumetric changes in the cerebellum cortex and white matter, thalamus, hippocampus, right putamen, left supramarginal and left lingual regions. Overall, results suggest that not only the PSQI global score may act as a proxy of changes in FC/SC in middle-aged and older individuals, but also that the age-related regional volumetric changes may be associated to an adjustment of brain connectivity. These findings may also represent a step further in the comprehension of the role of sleep disturbance in disease, since the networks found share regions that have been shown to be affected in pathologies, such as depression and Alzheimer's disease.

Subjective-Objective Sleep Discrepancy Is Associated With Alterations in Regional Glucose Metabolism in Patients With Insomnia and Good Sleeper Controls

Objectives

Sleep discrepancies are common in primary insomnia (PI) and include reports of longer sleep onset latency (SOL) than measured by polysomnography (PSG) or "negative SOL discrepancy." We hypothesized that negative SOL discrepancy in PI would be associated with higher relative glucose metabolism during nonrapid eye movement (NREM) sleep in brain networks involved in conscious awareness, including the salience, left executive control, and default mode networks.

Methods

PI (n = 32) and good sleeper controls (GS; n = 30) completed [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) scans during NREM sleep, and relative regional cerebral metabolic rate for glucose (rCMRglc) was measured. Sleep discrepancy was calculated by subtracting PSG-measured SOL on the PET night from corresponding self-report values the following morning. We tested for interactions between group (PI vs. GS) and SOL discrepancy for rCMRglc during NREM sleep using both a region of interest mask and exploratory whole-brain analyses.

Results

Significant group by SOL discrepancy interactions for rCMRglc were observed in several brain regions (pcorrected < .05 for all clusters). In the PI group, more negative SOL discrepancy (self-reported > PSG-measured SOL) was associated with significantly higher relative rCMRglc in the right anterior insula and middle/posterior cingulate during NREM sleep. In GS, more positive SOL discrepancy (self-reported < PSG-measured SOL) was associated with significantly higher relative rCMRglc in the right anterior insula, left anterior cingulate cortex, and middle/posterior cingulate cortex.

Conclusions

Although preliminary, these findings suggest regions of the brain previously shown to be involved in conscious awareness, and the perception of PSG-defined states may also be involved in the phenomena of SOL discrepancy.

The association between insomnia-related sleep disruptions and cognitive dysfunction during the inter-episode phase of bipolar disorder

Sleep disturbance and cognitive dysfunction are two domains of impairment during inter-episode bipolar disorder. Despite evidence demonstrating the importance of sleep for cognition in healthy and sleep-disordered samples, this link has been minimally examined in bipolar disorder. The present study tested the association between insomnia-related sleep disruptions and cognitive dysfunction during inter-episode bipolar disorder. Forty-seven participants with bipolar disorder and a comorbid insomnia diagnosis (BD-Insomnia) and 19 participants with bipolar disorder without sleep disturbance in the last six months (BD-Control) participated in the study. Two domains of cognition were assessed: working memory and verbal learning. Insomnia-related sleep disruptions were assessed both categorically (i.e., insomnia diagnosis) and dimensionally (i.e., total wake time, total sleep time, total wake time variability, and total sleep time variability). Hierarchical linear regressions, adjusting for participant age, demonstrated that insomnia diagnosis did not have an independent or interactive effect on cognition. However, regardless of insomnia diagnosis, greater total sleep time variability predicted poorer working memory and verbal learning performance. Further, following sleep treatment, a reduction in total wake time predicted improved working memory performance and a reduction in total sleep time variability predicted improved verbal learning performance. These findings raise the possibility that sleep disturbance may contribute to cognitive dysfunction in bipolar disorder and highlight the importance of treating sleep disturbance in bipolar disorder.

Preliminary investigation of the relationships between sleep duration, reward circuitry function, and mood dysregulation in youth offspring of parents with bipolar disorder

BACKGROUND

Altered reward circuitry function is observed in individuals with bipolar disorder (BD) and their unaffected offspring (OBP). While OBP are at elevated risk for BD, modifiable risk factors that may exacerbate neural vulnerabilities in OBP remain under-characterized. As sleep loss is strongly linked to mania in BD, this study tested associations between sleep duration, reward circuitry function, and mood dysregulation in OBP.

METHODS

Two groups of youth unaffected with BD (9-17yr) completed a number-guessing fMRI reward paradigm: 25 OBP and 21 age-sex-IQ-matched offspring of control parents with non-BD psychopathology (OCP), to differentiate risk for BD from risk for psychopathology more broadly. Regressions tested effects of group status, self-reported past-week sleep duration, and their interaction on neural activity and bilateral ventral striatum (VS) functional connectivity to win>control. Correlations with parent-reported mood dysregulation were assessed.

RESULTS

Group effects were observed for right posterior insula activity (OCP>OBP) and VS-left posterior insula connectivity (OBP>OCP). Group^⁎sleep duration interactions were observed for left dorsal anterior-mid-cingulate (daMCC) activity and VS-left anterior insula/ventrolateral prefrontal cortex (VLPFC) connectivity. Specifically, sleep duration and daMCC activity were positively related in OBP, but negatively related in OCP and sleep duration and VS-left anterior insula/VLPFC connectivity were negatively related in OBP, but positively in OCP. Additionally, increased VS-left posterior insula connectivity and VS-left anterior insula/VLPFC connectivity were associated with greater mood dysregulation in OBP only.

LIMITATIONS

Cross-sectional design and small sample size.

CONCLUSIONS

Altered reward-related VS-insula connectivity could represent a neural pathway underpinning mood dysregulation in OBP, and may be modulated by shortened sleep duration.

Sleep Fragmentation Does Not Explain Misperception of Latency or Total Sleep Time

STUDY OBJECTIVES

Perception of sleep-wake times may differ from objective measures, although the mechanisms remain elusive. Quantifying the misperception phenotype involves two operational challenges: defining objective sleep latency and treating sleep latency and total sleep time as independent factors. We evaluated a novel approach to address these challenges and test the hypothesis that sleep fragmentation underlies misperception.

METHODS

We performed a retrospective analysis on patients with or without obstructive sleep apnea during overnight diagnostic polysomnography in our laboratory (n = 391; n = 252). We compared subjective and objective sleep-wake durations to characterize misperception. We introduce a new metric, sleep during subjective latency (SDSL), which captures latency misperception without defining objective sleep latency and allows correction for latency misperception when assessing total sleep time (TST) misperception.

RESULTS

The stage content of SDSL is related to latency misperception, but in the opposite manner as our hypothesis: those with > 20 minutes of SDSL had less N1%, more N3%, and lower transition frequency. After adjusting for misperceived sleep during subjective sleep latency, TST misperception was greater in those with longer bouts of REM and N2 stages (OSA patients) as well as N3 (non-OSA patients), which also did not support our hypothesis.

CONCLUSIONS

Despite the advantages of SDSL as a phenotyping tool to overcome operational issues with quantifying misperception, our results argue against the hypothesis that light or fragmented sleep underlies misperception. Further investigation of sleep physiology utilizing alternative methods than that captured by conventional stages may yield additional mechanistic insights into misperception.

COMMENTARY

A commentary on this article appears in this issue on page 1211.

Sleep Duration and Cancer in the NIH-AARP Diet and Health Study Cohort

Background

Very few studies have examined sleep duration in relation to cancer incidence with the exception of breast cancer.

Methods

We assessed the associations between sleep duration and incidences of total and 18 site-specific cancers in the NIH-AARP Health and Diet Study cohort, with 173,327 men and 123,858 women aged 51–72 years at baseline. Self-reported sleep duration categories were assessed via questionnaire. We used multivariable Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI), using 7–8 hours/night as the reference.

Results

We observed a significantly increased risk of stomach cancer among male short sleepers (multivariable HR_{5-6 vs. 7–8 hours} = 1.29; 95%CI: 1.05, 1.59; P_trend = 0.03). We also observed suggestive associations in either short or long sleepers, which did not reach overall significance (P_trend >0.05), including increased risks in male short sleepers for cancers of head and neck (HR_{<5vs.7-8 hours} = 1.39; 95%CI:1.00–1.95), bladder (HR_{5-6vs.7-8 hours} = 1.10; 95%CI:1.00–1.20), thyroid (HR_{<5 vs. 7–8 hours} = 2.30; 95%CI:1.06, 5.02), Non-Hodgkin Lymphoma (NHL) (HR_{5-6vs.7-8 hours} = 1.17; 95%CI:1.02–1.33), and myeloma (HR_{<5vs.7-8 hours} = 2.06; 95%CI:1.20–3.51). In women, the suggestive associations include a decreased total cancer risk (HR_{<5vs.7-8 hours} = 0.9; 95%CI:0.83–0.99) and breast cancer risk (HR_{<5vs.7-8 hours} = 0.84; 95%CI:0.71–0.98) among short sleepers. A decreased ovarian cancer risk (HR_{≥ 9 vs. 7–8 hours} = 0.50; 95%CI:0.26–0.97) and an increased NHL risk (HR_{≥ 9 vs. 7–8 hours} = 1.45; 95%CI:1.00–2.11) were observed among long sleepers.

Conclusion

In an older population, we observed an increased stomach cancer risk in male short sleepers and suggestive associations with short or long sleep duration for many cancer risks in both genders.

24-HOUR ACTIVITY RHYTHM AND SLEEP DISTURBANCES IN DEPRESSION AND ANXIETY: A POPULATION-BASED STUDY OF MIDDLE-AGED AND OLDER PERSONS

BACKGROUND

Disturbed circadian rhythms have been associated with depression and anxiety, but it is unclear if disturbances in the 24-hr activity rhythm and sleep are independently and specifically related to these disorders.

METHODS

In 1,714 middle-aged and elderly participants of the Rotterdam Study, we collected actigraphy recordings of at least 96 hr (138 ± 14 hr, mean ± standard deviation). Activity rhythms were quantified calculating the fragmentation of the rhythm, stability of the rhythm over days, and timing of the rhythm. Total sleep time, sleep onset latency, and wake after sleep onset were also estimated with actigraphy. Depressive symptoms were assessed with the Center for Epidemiologic Studies Depression scale, persons with clinically relevant depressive symptoms were interviewed to diagnose DSM-IV-depressive disorder. Anxiety disorders were determined with the Munich version of the Composite International Diagnostic Interview.

RESULTS

More fragmented rhythms were associated with clinically relevant depressive symptoms (odds ratio (OR): 1.27, 95% confidence interval (CI): 1.04;1.54) and anxiety disorders (OR: 1.39, 95% CI: 1.14;1.70) after covariate adjustment. Less stable rhythms, longer sleep onset latency, and more wake after sleep onset were related to clinically relevant depressive symptoms or anxiety disorders only if not adjusted for covariates and other activity rhythm and sleep indicators.

CONCLUSIONS

Our study in middle-aged and elderly persons suggests that fragmentation of the 24-hr activity rhythm is associated with depression and anxiety. Moreover, this association also largely accounts for the effect of disturbed sleep on these psychiatric disorders.

Sleep-wake time perception varies by direct or indirect query

STUDY OBJECTIVES

The diagnosis of insomnia rests on self-report of difficulty initiating or maintaining sleep. However, subjective reports may be unreliable, and possibly may vary by the method of inquiry. We investigated this possibility by comparing within-individual response to direct versus indirect time queries after overnight polysomnography.

METHODS

We obtained self-reported sleep-wake times via morning questionnaires in 879 consecutive adult diagnostic polysomnograms. Responses were compared within subjects (direct versus indirect query) and across groups defined by apnea-hypopnea index and by self-reported insomnia symptoms in pre-sleep questionnaires. Direct queries required a time duration response, while indirect queries required clock times from which we calculated time durations.

RESULTS

Direct and indirect queries of sleep latency were the same in only 41% of cases, and total sleep time queries matched in only 5.4%. For both latency and total sleep, the most common discrepancy involved the indirect value being larger than the direct response. The discrepancy between direct and indirect queries was not related to objective sleep metrics. The degree of discrepancy was not related to the presence of insomnia symptoms, although patients reporting insomnia symptoms showed underestimation of total sleep duration by direct response.

CONCLUSIONS

Self-reported sleep latency and total sleep time are often internally inconsistent when comparing direct and indirect survey queries of each measure. These discrepancies represent substantive challenges to effective clinical practice, particularly when diagnosis and management depends on self-reported sleep patterns, as with insomnia. Although self-reported sleep-wake times remains fundamental to clinical practice, objective measures provide clinically relevant adjunctive information.

Prevalence and clinical correlates of co-occurring insomnia and hypersomnia symptoms in depression

BACKGROUND

The aim was to examine the prevalence and consequences of co-occurring insomnia and hypersomnia symptoms in depressed adults drawn from a representative sample of the U.S. population.

METHOD

Data from 687 National Comorbidity Survey Replication (NCS-R) respondents meeting criteria for a major depressive episode (MDE) in the past year were included. Respondents completed clinical interviews that assessed 12-month DSM-IV disorders, impairment, mental health treatment, and depressive symptom severity. Outcomes were compared between respondents who experienced insomnia symptoms-only (N=404), hypersomnia symptoms-only (N=44), both insomnia and hypersomnia symptoms (N=184) and no sleep problems (N=55) during an MDE.

RESULTS

Insomnia and hypersomnia symptoms co-occurred in 27.7% of respondents with past-year MDEs, most frequently in bipolar spectrum disorders and major depressive disorder with dysthymia. Similar to the insomnia-only group, respondents with co-occurring sleep disturbances had more severe depression, and higher rates of past-year impulse control disorders and suicide planning. Similar to the hypersomnia-only group, respondents with co-occurring sleep disturbances had higher rates of past-year drug use disorders and suicide attempts. Compared to the insomnia-only and no sleep problem groups, respondents with both sleep disturbances were more frequently in mental health treatment, seeing a general practitioner, and taking antidepressants.

LIMITATIONS

The NCS-R is cross-sectional and did not evaluate sleep disorder diagnoses.

CONCLUSIONS

Co-occurring insomnia and hypersomnia symptoms were associated with a more severe MDE. Further research is warranted to more fully understand the joint presentation of insomnia and hypersomnia in depression.

Social, behavioral, and sleep characteristics associated with depression symptoms among undergraduate students at a women's college: a cross-sectional depression survey, 2012

Background

The association between student characteristics and depression among students attending women’s colleges (single-sex institutions of higher education that exclude or limit males from admission) is poorly understood. Our objective was to estimate the prevalence of depression and determine behavioral and social characteristics associated with depression among students attending a women’s college.

Methods

We administered a cross-sectional Internet-based survey between April and May 2012 to students (n = 277) enrolled at a private women’s college in the southeastern US. Center for Epidemiologic Studies Depression (CES-D) and Depression Anxiety Stress Scale 21 (DASS-21) instruments measured self-reported depression. Bivariate and multivariable logistic regression methods were used to estimate adjusted associations.

Results

Prevalence of depression measured by CES-D and DASS-21 instruments was 26.3% (95% confidence interval [CI] 20.8-32.3%) and 26.0% (95% CI 20.4-32.3%), respectively. After adjusting for confounders, absence of strong social support (prevalence odds ratio [OR] = 4.3, 95% CI 1.4-13.7), history of mental health disorder (OR = 4.8 95% CI 1.9-12.4), and poor sleep hygiene (OR = 2.8, 95% CI 1.3-5.8) were associated with depression.

Conclusions

This cross-sectional survey identified absence of strong social support, history of mental health disorder, and poor sleep hygiene as potential predictors of depression among students attending a women’s college. Further investigation of these factors may inform depression interventions for students attending women’s colleges and other undergraduate student populations.

(Mis)perception of sleep in insomnia: a puzzle and a resolution

Insomnia is prevalent, causing severe distress and impairment. This review focuses on illuminating the puzzling finding that many insomnia patients misperceive their sleep. They overestimate their sleep onset latency (SOL) and underestimate their total sleep time (TST), relative to objective measures. This tendency is ubiquitous (although not universal). Resolving this puzzle has clinical, theoretical, and public health importance. There are implications for assessment, definition, and treatment. Moreover, solving the puzzle creates an opportunity for real-world applications of theories from clinical, perceptual, and social psychology as well as neuroscience. Herein we evaluate 13 possible resolutions to the puzzle. Specifically, we consider the possible contribution, to misperception, of (1) features inherent to the context of sleep (e.g., darkness); (2) the definition of sleep onset, which may lack sensitivity for insomnia patients; (3) insomnia being an exaggerated sleep complaint; (4) psychological distress causing magnification; (5) a deficit in time estimation ability; (6) sleep being misperceived as wake; (7) worry and selective attention toward sleep-related threats; (8) a memory bias influenced by current symptoms and emotions, a confirmation bias/belief bias, or a recall bias linked to the intensity/recency of symptoms; (9) heightened physiological arousal; (10) elevated cortical arousal; (11) the presence of brief awakenings; (12) a fault in neuronal circuitry; and (13) there being 2 insomnia subtypes (one with and one without misperception). The best supported resolutions were misperception of sleep as wake, worry, and brief awakenings. A deficit in time estimation ability was not supported. We conclude by proposing several integrative solutions.

Are sleep and depression independent or overlapping risk factors for cardiometabolic disease?

Sleep duration, sleep continuity, and depression are associated with cardiovascular disease and metabolic disorders. Despite the well-established relationship between sleep and depression, few studies examine these characteristics simultaneously in the development of cardiometabolic disease. Here, we review available studies that include measures of both sleep and depression in relation to cardiometabolic outcomes (cardiovascular disease, diabetes, and the metabolic syndrome). In general, data show that independent of depression, sleep continuity is a risk factor for cardiovascular disease, and short or long sleep duration is a risk factor for diabetes and the metabolic syndrome. Results for associations between sleep duration and cardiovascular disease, and associations between sleep continuity and metabolic disease, are more mixed. Regarding depression, there is preliminary evidence that depression increases risk for cardiovascular disease, independent of sleep continuity. However, there are insufficient data to address whether relationships between depression and cardiovascular and metabolic disease are independent of sleep duration. A number of biobehavioral mechanisms, including inflammation, hypothalamic and sympathetic dysregulation, and obesity and health behaviors, may account for the relationships among sleep, depression, and cardiometabolic disease. After summarizing these mechanisms, we discuss limitations of the extant literature and suggest directions for future research.

Association of sleep duration with mortality from cardiovascular disease and other causes for Japanese men and women: the JACC study

STUDY OBJECTIVES

To examine sex-specific associations between sleep duration and mortality from cardiovascular disease and other causes.

DESIGN

Cohort study.

SETTING

Community-based study.

PARTICIPANTS

A total of 98,634 subjects (41,489 men and 57,145 women) aged 40 to 79 years from 1988 to 1990 and were followed until 2003.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

During a median follow-up of 14.3 years, there were 1964 deaths (men and women: 1038 and 926) from stroke, 881 (508 and 373) from coronary heart disease, 4287 (2297 and 1990) from cardiovascular disease, 5465 (3432 and 2033) from cancer, and 14,540 (8548 and 5992) from all causes. Compared with a sleep duration of 7 hours, sleep duration of 4 hours or less was associated with increased mortality from coronary heart disease for women and noncardiovascular disease/noncancer and all causes in both sexes. The respective multivariable hazard ratios were 2.32 (1.19-4.50) for coronary heart disease in women, 1.49 (1.02-2.18) and 1.47 (1.01-2.15) for noncardiovascular disease/noncancer, and 1.29 (1.02-1.64) and 1.28 (1.03-1.60) for all causes in men and women, respectively. Long sleep duration of 10 hours or longer was associated with 1.5- to 2-fold increased mortality from total and ischemic stroke, total cardiovascular disease, noncardiovascular disease/noncancer, and all causes for men and women, compared with 7 hours of sleep in both sexes. There was no association between sleep duration and cancer mortality in either sex.

CONCLUSIONS

Both short and long sleep duration were associated with increased mortality from cardiovascular disease, noncardiovascular disease/noncancer, and all causes for both sexes, yielding a U-shaped relationship with total mortality with a nadir at 7 hours of sleep.

Pain and risk of completed suicide in Japanese men: a population-based cohort study in Japan (Ohsaki Cohort Study)

Unrelieved pain is a major factor that influences suicide risk among terminally ill patients, but little is known about the relationship between pain and the risk of completed suicide in the general population. We prospectively examined the association between self-reports of pain and subsequent risk of completed suicide in 26,481 men aged 40 to 79 years from the Ohsaki National Health Insurance Cohort study, a population-based, prospective cohort study initiated in 1994. On the basis of a five-item questionnaire on pain, individuals were classified as having no pain, very mild pain, mild pain, or moderate or severe pain. Completed suicide cases were documented from 1995 to 2001. During 131,027 person-years, 64 completed suicides were documented. After adjustment for covariates, the risk for completed suicide was significantly higher in the subjects with more pain. Multivariate hazard ratios (95% confidence intervals) relative to the subjects who had no pain were 1.36 (0.67-2.75), 2.11 (1.02-4.33), and 2.93 (1.34-6.42) in the subjects who had very mild pain, mild pain, and moderate or severe pain, respectively (P for trend=0.004). Stratified analysis showed that the positive association between pain and suicide risk was robust in the subjects with good health, low stress, adequate sleep, good physical activity, and no history of chronic diseases. Our results suggest that pain is associated with an increased risk of completed suicide among Japanese men. The association was consistently observed among apparently healthy subjects.

The parable of parabola: what the U-shaped curve can and cannot tell us about sleep

The Finnish Twin Cohort and in Great Britain, The Whitehall II Cohort--both endowed with rich covariate data. Associations between short and long sleep durations and mortality were first noted by Hammond in 1964 in the American Cancer Society I study, and they later achieved notoriety when presented by Kripke et al in 1979 (see reference 5 for a review of studies with similar findings.) Although the number and specificity of publications to further explore these controversial findings rapidly increased, most studies relied on the association of sleep duration measured at a single time point with followed-up mortality. Noteworthy in the Hublin et al and Ferrie et al studies is that participants were queried about their sleep durations at two different time points separated by intervals of 5 to 6 years, and mortality was assessed 22 and 12 years, respectively, subsequent to the second measurement. This feature effectively eliminates the possibility that the tails of the habitual sleep distribution (short or long sleep) were reflecting terminal illnesses or death-imminent processes, even in their most subtle stages. Only one prior study attempted to account for this limitation by eliminating deaths shortly after the ascertainment of sleep duration, but the two-year interval used may not have entirely eliminated this possibility. The repeated surveys in both Hublin et al and Ferrie et al demonstrate reliability in the subjects' answers over time, indicating that these were not spurious or "random" estimates of sleep duration. Furthermore, the repeated measures allowed investigation of change in sleep duration over time. Particularly interesting in Ferrie et al was that increases in sleep duration over time (from less than 5 to 7 hours or more) in some individuals was associated

Duration of sleep and breast cancer risk in a large population-based case–control study

One important function of sleep may be its contribution to the maintenance of the immune system and regulation of the circadian rhythms by melatonin. Researchers have speculated that disruption of immune functions involving cortisol levels and natural killer cell activity may increase breast cancer risk whereas increased melatonin exposure may protect against breast cancer. We conducted a multistate population-based case-control study of 4,033 women with invasive breast cancer and 5,314 community women without breast cancer in which we inquired about women's sleep habits in the recent past and during adult lifetime. Relative to women who slept 7.0-7.9 h/night, the multivariate odds ratio for developing breast cancer among women who slept an average of 9 h or more per night approximately 2 years prior to interview was 1.13 (95% CI 0.93-1.37). The multivariate-adjusted odds ratio for the continuous term was 1.06 (95% CI 1.01-1.11), suggesting a 6% increase in risk for every additional hour of sleep. Similar patterns were observed for average lifetime adult sleep duration. We found little evidence that sleeping few hours per night was associated with breast cancer risk. The results of this study suggest that increasing sleep duration is modestly associated with an increased breast cancer risk. In contrast, short duration of sleep (<7 h/night) is not substantially associated with increased risk. Further research in this area is warranted.

Long sleep and mortality: rationale for sleep restriction

Epidemiologic studies have consistently shown that sleeping >8 h per night is associated with increased mortality. Indeed, the most recent American Cancer Society data of 1.1 million respondents showed that sleeping longer than 7.5 h was associated with approximately 5% of the total mortality of the sample. The excess mortality was found even after controlling for 32 potentially confounding risk factors. Although epidemiologic data cannot prove that long sleep duration causes mortality, there is sufficient evidence to warrant future testing of the hypothesis that mild sleep restriction would decrease mortality in long sleepers. Sleep restriction might resemble dietary restriction as a potential aid to survival. Sleep restriction has several potential benefits besides possible enhanced survival. Acute sleep restriction can have dramatic antidepressant effects. Also, chronic sleep restriction is perhaps the most effective treatment for primary insomnia. Conversely, spending excessive time in bed can elicit daytime lethargy and exacerbate sleep fragmentation, resulting in a vicious cycle of further time in bed and further sleep fragmentation. Sleep restriction may be most beneficial for older adults, who tend to spend excessive time in bed and have more sleep fragmentation compared with young adults.

Quantifying subjective assessment of sleep and life-quality in antidepressant-treated depressed patients

This study sought to establish a method of quantifying subjective perceptions of sleep against perceptions of life-quality and mood, using amended versions of the Pittsburgh sleep diary (PghSD) and quality of life of insomniacs (QOLI) questionnaire. Diaries and questionnaires were self-completed in participants' homes. Outpatients with a DSM-IV diagnosis of major depressive disorder were compared with a healthy control group (with no history, or family history, of depression). Poorer sleepers, as determined by the sleep diary, were significantly more likely to report poorer life-quality and mood perceptions on the subsequent questionnaire. Furthermore, the depressed group reported significantly poorer perceptions of sleep quality and poorer perceptions of life-quality and mood than the control group, even though estimates of sleep disturbance were similar. This may indicate that depressed individuals experience more 'sleep distress' than healthy individuals. These results confirm the extent of subjectively reported sleep disruption in depression and demonstrate the merit of combining the amended PghSD and QOLI to quantify sleep perceptions.

Sleep duration, insomnia and behavioral problems among Chinese adolescents

This study examined the associations among sleep duration, insomnia, and behavioral problems in a sample of 1359 Chinese adolescents. Participants completed a self-administrated questionnaire that included questions on sleep duration and insomnia symptoms and the Youth Self-Report of Child Behavior Checklist. It was found that adolescents who complained of insomnia reported sleep duration only half an hour shorter than did those without insomnia. Sleep duration did not differ among adolescents reporting three different types of insomnia (difficulty initiating sleep, difficulty maintaining sleep, and early morning awakening). Adolescents with insomnia reported more behavioral problems than did those without complaints of insomnia. After adjustment for age and sex, sleep duration of less than 7 h a day was significantly associated with most behavioral problems in those without complaints of insomnia but with only a few behavioral problems in adolescents reporting insomnia. Results suggest that sleep duration in adolescents with insomnia is short, but not as short as reported in previous clinical studies. Insomnia and short sleep duration are associated with a wide range of behavioral and emotional problems in adolescents.

Sleep complaints predict coronary artery disease mortality in males: a 12-year follow-up study of a middle-aged Swedish population

OBJECTIVES

Only a few prospective surveys have been performed to investigate the relationship between sleep complaints and coronary artery disease (CAD) mortality. This study was conducted to determine whether sleep complaints in a middle-aged population predicted total mortality and CAD mortality.

DESIGN

A population-based prospective study. Setting. The County of Dalarna, Sweden.

SUBJECTS AND METHODS

In 1983, a random sample of 1870 subjects aged 45-65 years responded to a postal questionnaire (response rate 70.2%) including questions about sleep complaints and various diseases. Mortality data for the period 1983-95 were collected, and Cox proportional hazard analyses were used to examine the mortality risks.

RESULTS

At 12-year follow-up 165 males (18.2%) and 101 females (10.5%) had died. After adjustment for a wide range of important putative risk factors, difficulties initiating sleep (DIS) were related to CAD death in males [relative risk (RR), 3.1; 95% confidence interval (CI), 1.5-6.3; P < 0.01], but not in females. Short or long sleep duration did not influence risk of CAD mortality or total mortality for either gender. Depression in males increased the risk of death attributed to CAD (RR, 3.0; 95% CI, 1.1-8.4; P < 0.05) and total mortality (RR, 2.2; 95% CI, 1.1-4.5; P < 0.05).

CONCLUSION

These results provide evidence that there is an association between difficulties falling asleep and CAD mortality in males.

Sleep disturbances in patients with Alzheimer's disease: epidemiology, pathophysiology and treatment

Older adults represent an ever-growing proportion of the population of the industrialised nations, with a corresponding increase in the numbers of patients with dementing disorders. A common complaint in both normal aging and the dementias is that of significant sleep disturbance. The major causes of sleep disruption in aging and dementia include: (i) physiological changes that arise as part of normal, 'nonpathological' aging; (ii) sleep problems due to one of many physical or mental health conditions and their treatments; (iii) primary sleep disorders; (iv) poor 'sleep hygiene', that is, sleep-related practices and habits; and (v) some combination of these factors. Disrupted sleep in patients with dementia is a significant cause of stress for caregivers and frequently leads to institutionalisation of patients. It should be a target of clinical management when the goal is sustained home care, and when it is associated with disturbances of mood or behaviour. While the neuropathology of dementia can directly disrupt sleep, sleep disturbances in patients with dementia often have multiple causes that require systematic evaluation. Thorough assessment of associated psychopathology, day-time behaviour, medical disorders, medications, pain and environmental conditions is needed for optimal management. Differential diagnosis of a sleep problem in dementia is the basis of rational pharmacotherapy. However, patients with dementia are likely to be more sensitive than elderly persons without dementia to adverse cognitive and motor effects of drugs prescribed for sleep. Clinicians need to: (i) evaluate sleep outcomes when treating medical, psychiatric and behavioural disorders in older adults; (ii) be alert to emerging behavioural and environmental approaches to treatment; (iii) combine nonpharmacological strategies with drug therapies, when required, for added value; and (iv) avoid use of multiple psychotropic medications unless they prove essential to the adequate management of sleep disturbances.

Treatment of sleep disturbance in Alzheimer's disease

The prevalence of Alzheimer's disease (AD) is rapidly increasing as growing numbers of people around the world are living to old age. Sleep disturbances are a common, and often highly disruptive, behavioral symptom associated with AD. Nevertheless, the study of sleep in AD is relatively new. Little is known about the moderating factors that may alter a given patient's risk for developing sleep problems, or that may influence severity of presentation and persistence. Current treatments for improving sleep in AD fall into three broad categories: (i) pharmacological; (ii) cognitive-behavioral or psycho-educational strategies; and (iii) biological/circadian therapies. There are few studies demonstrating the efficacy of these treatments with community-dwelling AD patients, although studies with persons in institutional settings are promising. In this review, it is suggested that sleep problems in AD are multi-factorial, and influenced by a variety of demographic, physical, psychiatric and situational factors. These factors vary in how readily they can be modified and in how relevant they are to any individual case. Thus, when developing a treatment plan for sleep problems in a dementia patient, it is important to evaluate the underlying causes as well as the context in which the problems are occurring, and to target the intervention accordingly.

Circadian sleep, illumination, and activity patterns in women: influences of aging and time reference

Patterns of sleep, illumination, and activity of women of different ages were continuously monitored in their natural environments with a wrist activity monitor. Partial correlation analyses were performed to determine relationships between age and sleep and several circadian rhythm measures including the amplitudes, mesors, and timings of sleep, of illumination, and of activity. We found no age-related decline in actigraphic sleep duration. Age was not a significant correlate of circadian rhythm parameters of sleep. Moreover, no age effects were found on daily illumination exposure or on the circadian timing of illumination and activity patterns. However, the level and amplitude of the circadian activity rhythm showed a gradual decline with aging, independent of the time reference (i.e., Daylight Saving Time versus Standard Time) when recordings were obtained. As expected, significant associations were observed between local time reference and the level and timing of peak of illumination patterns. However, changes in local time reference were not significantly and consistently associated with actigraphic sleep or activity measures.

Symptoms of psychological distress predict 7-year mortality

As part of the Health and Lifestyle Survey (HALS), 6096 adults from a representative sample of community residents completed a standardized questionnaire which elicited psychiatric symptoms--the General Health Questionnaire (GHQ-30) of Goldberg (1972). Their survival status at 7 years was determined, and 474 had died. Respondents whose GHQ score was above the conventional threshold (4/5), used when screening for psychiatric disorder, were 60% more likely to die over the 7-year interval than respondents whose GHQ score was below threshold (risk ratio 1.64 for men and 1.58 for women). The differences were statistically significant for both sexes when the effects of age, physical disorder, social class and smoking behaviour were taken into account. Personality traits (neuroticism, extraversion) were not related to mortality, neither was self-reported difficulty in sleeping. However, a low subjective rating of one's general health was associated with increased mortality. We explored a range of cut-points and found reliable effects for both sexes at all cut-points from 3/4 to 6/7. Possible differences related to natural versus unnatural causes of death were explored and found not to explain the results. The findings from this general population study confirm that is is not only psychiatric disorders, but also psychiatric symptoms, which are associated with subsequent mortality, and thereby reinforce the importance of appropriate intervention to alleviate these symptoms.