Sleep in mood disorders

Sleep, plasticity and memory from molecules to whole-brain networks

Despite the ubiquity of sleep across phylogeny, its function remains elusive. In this review, we consider one compelling candidate: brain plasticity associated with memory processing. Focusing largely on hippocampus-dependent memory in rodents and humans, we describe molecular, cellular, network, whole-brain and behavioral evidence establishing a role for sleep both in preparation for initial memory encoding, and in the subsequent offline consolidation of memory. Sleep and sleep deprivation bidirectionally alter molecular signaling pathways that regulate synaptic strength and control plasticity-related gene transcription and protein translation. At the cellular level, sleep deprivation impairs cellular excitability necessary for inducing synaptic potentiation and accelerates the decay of long-lasting forms of synaptic plasticity. In contrast, rapid eye movement (REM) and non-rapid eye movement (NREM) sleep enhance previously induced synaptic potentiation, although synaptic de-potentiation during sleep has also been observed. Beyond single cell dynamics, large-scale cell ensembles express coordinated replay of prior learning-related firing patterns during subsequent NREM sleep. At the whole-brain level, somewhat analogous learning-associated hippocampal (re)activation during NREM sleep has been reported in humans. Moreover, the same cortical NREM oscillations associated with replay in rodents also promote human hippocampal memory consolidation, and this process can be manipulated using exogenous reactivation cues during sleep. Mirroring molecular findings in rodents, specific NREM sleep oscillations before encoding refresh human hippocampal learning capacity, while deprivation of sleep conversely impairs subsequent hippocampal activity and associated encoding. Together, these cross-descriptive level findings demonstrate that the unique neurobiology of sleep exerts powerful effects on molecular, cellular and network mechanisms of plasticity that govern both initial learning and subsequent long-term memory consolidation.

NREM and REM Sleep: Complementary Roles in Recovery after Wakefulness

The overall function of sleep is hypothesized to provide "recovery" after preceding waking activities, thereby ensuring optimal functioning during subsequent wakefulness. However, the functional significance of the temporal dynamics of sleep, manifested in the slow homeostatic process and the alternation between non-rapid eye movement (NREM) and REM sleep remains unclear. We propose that NREM and REM sleep have distinct and complementary contributions to the overall function of sleep. Specifically, we suggest that cortical slow oscillations, occurring within specific functionally interconnected neuronal networks during NREM sleep, enable information processing, synaptic plasticity, and prophylactic cellular maintenance ("recovery process"). In turn, periodic excursions into an activated brain state-REM sleep-appear to be ideally placed to perform "selection" of brain networks, which have benefited from the process of "recovery," based on their offline performance. Such two-stage modus operandi of the sleep process would ensure that its functions are fulfilled according to the current need and in the shortest time possible. Our hypothesis accounts for the overall architecture of normal sleep and opens up new perspectives for understanding pathological conditions associated with abnormal sleep patterns.

The role of sleep in emotional brain function

Rapidly emerging evidence continues to describe an intimate and causal relationship between sleep and emotional brain function. These findings are mirrored by long-standing clinical observations demonstrating that nearly all mood and anxiety disorders co-occur with one or more sleep abnormalities. This review aims to (a) provide a synthesis of recent findings describing the emotional brain and behavioral benefits triggered by sleep, and conversely, the detrimental impairments following a lack of sleep; (b) outline a proposed framework in which sleep, and specifically rapid-eye movement (REM) sleep, supports a process of affective brain homeostasis, optimally preparing the organism for next-day social and emotional functioning; and (c) describe how this hypothesized framework can explain the prevalent relationships between sleep and psychiatric disorders, with a particular focus on posttraumatic stress disorder and major depression.

So depression is an inflammatory disease, but where does the inflammation come from?

BACKGROUND

We now know that depression is associated with a chronic, low-grade inflammatory response and activation of cell-mediated immunity, as well as activation of the compensatory anti-inflammatory reflex system. It is similarly accompanied by increased oxidative and nitrosative stress (O&NS), which contribute to neuroprogression in the disorder. The obvious question this poses is 'what is the source of this chronic low-grade inflammation?'

DISCUSSION

This review explores the role of inflammation and oxidative and nitrosative stress as possible mediators of known environmental risk factors in depression, and discusses potential implications of these findings. A range of factors appear to increase the risk for the development of depression, and seem to be associated with systemic inflammation; these include psychosocial stressors, poor diet, physical inactivity, obesity, smoking, altered gut permeability, atopy, dental cares, sleep and vitamin D deficiency.

SUMMARY

The identification of known sources of inflammation provides support for inflammation as a mediating pathway to both risk and neuroprogression in depression. Critically, most of these factors are plastic, and potentially amenable to therapeutic and preventative interventions. Most, but not all, of the above mentioned sources of inflammation may play a role in other psychiatric disorders, such as bipolar disorder, schizophrenia, autism and post-traumatic stress disorder.

Mood and metabolic consequences of sleep deprivation as a potential endophenotype' in bipolar disorder

It has been commonly recognized that circadian rhythm and sleep/wake cycle are causally involved in bipolar disorder. There has been a paucity of systematic research considering the relations between sleep and mood states in bipolar disorder. The current study examines the possible influences of sleep deprivation on mood states and endocrine functions among first-degree relatives of patients with bipolar disorder and healthy controls. Blood samples were taken at two time points in the consecutive mornings at predeprivation and postdeprivation periods. Participants simultaneously completed the Profiles of Mood States at two time points after giving blood samples. Plasma T3 and TSH levels increased after total sleep deprivation in both groups. Sleep deprivation induced TSH levels were reversely associated with depression-dejection among healthy controls. A paradoxical effect was detected for only the first-degree relatives of the patients that changes in plasma cortisol levels negatively linked to depression-dejection and anger-hostility scores after total sleep deprivation. Plasma DHEA levels became correlated with vigor-activity scores after sleep deprivation among first-degree relatives of bipolar patients. On the contrary, significant associations of depression-dejection, anger-hostility, and confusion-bewilderment with the baseline plasma DHEA levels became statistically trivial in the postdeprivation period. Findings suggested that first-degree relatives of patients with bipolar disorder had completely distinct characteristics with respect to sleep deprivation induced responses in terms of associations between endocrine functions and mood states as compared to individuals whose relatives had no psychiatric problems. Considering the relationships between endocrine functions and mood states among relatives of the patients, it appears like sleep deprivation changes the receptor sensitivity which probably plays a pivotal role on mood outcomes among the first-degree relatives of patients with bipolar disorder.

Delirium: a disturbance of circadian integrity?

Delirium is a serious neuropsychiatric syndrome of acute onset that occurs in approximately one in five general hospital patients and is associated with serious adverse outcomes that include loss of adaptive function, persistent cognitive problems and increased mortality. Recent studies indicate a three-domain model for delirium that includes generalised cognitive impairment, disturbed executive cognition, and disruption of behaviours that are under circadian control such as sleep-wake cycle and motor activity levels. As a consequence, attention has focused upon the possible role of the circadian timing system (CTS) in the pathophysiology of delirium. We explored this possibility by reviewing evidence that (1) many symptoms that occur in delirium are influenced by circadian rhythms, (2) many features of recognised circadian rhythm disorders are similar to characteristic features of delirium, (3) common risk factors for delirium are known to disrupt circadian systems, (4) physiological disturbances of circadian systems have been noted in delirious patients, and (5) positive effects in the treatment of delirium have been demonstrated for melatonin and related agents that influence the circadian timing system. A programme of future studies that can help to clarify the relevance of circadian integrity to delirium is described. Such work can provide a better understanding of the pathophysiology of delirium while also identifying opportunities for more targeted therapeutic efforts.

Chronobiology, endocrinology, and energy- and food-reward homeostasis

Energy- and food-reward homeostasis is the essential component for maintaining energy balance and its disruption may lead to metabolic disorders, including obesity and diabetes. Circadian alignment, quality sleep and sleep architecture in relation to energy- and food-reward homeostasis are crucial. A reduced sleep duration, quality sleep and rapid-eye movement sleep affect substrate oxidation, leptin and ghrelin concentrations, sleeping metabolic rate, appetite, food reward, hypothalamic-pituitary-adrenal (HPA)-axis activity, and gut-peptide concentrations, enhancing a positive energy balance. Circadian misalignment affects sleep architecture and the glucose-insulin metabolism, substrate oxidation, homeostasis model assessment of insulin resistance (HOMA-IR) index, leptin concentrations and HPA-axis activity. Mood disorders such as depression occur; reduced dopaminergic neuronal signaling shows decreased food reward. A good sleep hygiene, together with circadian alignment of food intake, a regular meal frequency, and attention for protein intake or diets, contributes in curing sleep abnormalities and overweight/obesity features by preventing overeating; normalizing substrate oxidation, stress, insulin and glucose metabolism including HOMA-IR index, and leptin, GLP-1 concentrations, lipid metabolism, appetite, energy expenditure and substrate oxidation; and normalizing food reward. Synchrony between circadian and metabolic processes including meal patterns plays an important role in the regulation of energy balance and body-weight control. Additive effects of circadian alignment including meal patterns, sleep restoration, and protein diets in the treatment of overweight and obesity are suggested.

Topographic and sex-related differences in sleep spindles in major depressive disorder: a high-density EEG investigation

BACKGROUND

Sleep spindles are believed to mediate several sleep-related functions including maintaining disconnection from the external environment during sleep, cortical development, and sleep-dependent memory consolidation. Prior studies that have examined sleep spindles in major depressive disorder (MDD) have not demonstrated consistent differences relative to control subjects, which may be due to sex-related variation and limited spatial resolution of spindle detection. Thus, this study sought to characterize sleep spindles in MDD using high-density electroencephalography (hdEEG) to examine the topography of sleep spindles across the cortex in MDD, as well as sex-related variation in spindle topography in the disorder.

METHODS

All-night hdEEG recordings were collected in 30 unipolar MDD participants (19 women) and 30 age and sex-matched controls. Topography of sleep spindle density, amplitude, duration, and integrated spindle activity (ISA) were assessed to determine group differences. Spindle parameters were compared between MDD and controls, including analysis stratified by sex.

RESULTS

As a group, MDD subjects demonstrated significant increases in frontal and parietal spindle density and ISA compared to controls. When stratified by sex, MDD women demonstrated increases in frontal and parietal spindle density, amplitude, duration, and ISA; whereas MDD men demonstrated either no differences or decreases in spindle parameters.

LIMITATIONS

Given the number of male subjects, this study may be underpowered to detect differences in spindle parameters in male MDD participants.

CONCLUSIONS

This study demonstrates topographic and sex-related differences in sleep spindles in MDD. Further research is warranted to investigate the role of sleep spindles and sex in the pathophysiology of MDD.

Qualitative study of the quality of sleep in marginalized individuals living with HIV

Sleep disturbances have been reported to be higher in human immunodeficiency virus (HIV)-infected individuals compared to the general population. Despite the consequences of poor quality of sleep (QOS), research regarding sleep disturbances in HIV infection is lacking and many questions regarding correlates of poor QOS, especially in marginalized populations, remain unanswered. We conducted one-on-one qualitative interviews with 14 marginalized HIV-infected individuals who reported poor QOS to examine self-reported correlates of sleep quality and explore the relationship between QOS and antiretroviral adherence. Findings suggest a complex and multidimensional impact of mental health issues, structural factors, and physical conditions on QOS of these individuals. Those reporting poor QOS as a barrier to antiretroviral adherence reported lower adherence due to falling asleep or feeling too tired to take medications in comparison to those who did not express this adherence barrier. These interviews underscore the importance of inquiries into a patient's QOS as an opportunity to discuss topics such as adherence, depression, suicidal ideation, and substance use.

Sleep education during pregnancy for new mothers

Background

There is a high association between disturbed (poor quality) sleep and depression, which has lead to a consensus that there is a bidirectional relationship between sleep and mood. One time in a woman’s life when sleep is commonly disturbed is during pregnancy and following childbirth. It has been suggested that sleep disturbance is another factor that may contribute to the propensity for women to become depressed in the postpartum period compared to other periods in their life. Post Natal Depression (PND) is common (15.5%) and associated with sleep disturbance, however, no studies have attempted to provide a sleep-focused intervention to pregnant women and assess whether this can improve sleep, and consequently maternal mood post-partum. The primary aim of this research is to determine the efficacy of a brief psychoeducational sleep intervention compared with a control group to improve sleep management, with a view to reduce depressive symptoms in first time mothers.

Method

This randomised controlled trial will recruit 214 first time mothers during the last trimester of their pregnancy. Participants will be randomised to receive either a set of booklets (control group) or a 3hour psychoeducational intervention that focuses on sleep. The primary outcomes of this study are sleep-related, that is sleep quality and sleepiness for ten months following the birth of the baby. The secondary outcome is depressive symptoms. It is hypothesised that participants in the intervention group will have better sleep quality and sleepiness in the postpartum period than women in the control condition. Further, we predict that women who receive the sleep intervention will have lower depression scores postpartum compared with the control group.

Discussion

This study aims to provide an intervention that will improve maternal sleep in the postpartum period. If sleep can be effectively improved through a brief psychoeducational program, then it may have a protective role in reducing maternal postpartum depressive symptoms.

Registration details

This trial is registered with the Australian New Zealand Clinical Trials Register under the registration number ACTRN12611000859987

Pharmacological validation of candidate causal sleep genes identified in an N2 cross

Despite the substantial impact of sleep disturbances on human health and the many years of study dedicated to understanding sleep pathologies, the underlying genetic mechanisms that govern sleep and wake largely remain unknown. Recently, the authors completed large-scale genetic and gene expression analyses in a segregating inbred mouse cross and identified candidate causal genes that regulate the mammalian sleep-wake cycle, across multiple traits including total sleep time, amounts of rapid eye movement (REM), non-REM, sleep bout duration, and sleep fragmentation. Here the authors describe a novel approach toward validating candidate causal genes, while also identifying potential targets for sleep-related indications. Select small-molecule antagonists and agonists were used to interrogate candidate causal gene function in rodent sleep polysomnography assays to determine impact on overall sleep architecture and to evaluate alignment with associated sleep-wake traits. Significant effects on sleep architecture were observed in validation studies using compounds targeting the muscarinic acetylcholine receptor M3 subunit (Chrm3) (wake promotion), nicotinic acetylcholine receptor alpha4 subunit (Chrna4) (wake promotion), dopamine receptor D5 subunit (Drd5) (sleep induction), serotonin 1D receptor (Htr1d) (altered REM fragmentation), glucagon-like peptide-1 receptor (Glp1r) (light sleep promotion and reduction of deep sleep), and calcium channel, voltage-dependent, T type, alpha 1I subunit (Cacna1i) (increased bout duration of slow wave sleep). Taken together, these results show the complexity of genetic components that regulate sleep-wake traits and highlight the importance of evaluating this complex behavior at a systems level. Pharmacological validation of genetically identified putative targets provides a rapid alternative to generating knock out or transgenic animal models, and may ultimately lead towards new therapeutic opportunities.

Altered sleep and affect in the neurotensin receptor 1 knockout mouse

STUDY OBJECTIVE

Sleep and mood disorders have long been understood to have strong genetic components, and there is considerable comorbidity of sleep abnormalities and mood disorders, suggesting the involvement of common genetic pathways. Here, we examine a candidate gene implicated in the regulation of both sleep and affective behavior using a knockout mouse model.

DESIGN

Previously, we identified a quantitative trait locus (QTL) for REM sleep amount, REM sleep bout number, and wake amount in a genetically segregating population of mice. Here, we show that traits mapping to this QTL correlated with an expression QTL for neurotensin receptor 1 (Ntsr1), a receptor for neurotensin, a ligand known to be involved in several psychiatric disorders. We examined sleep as well as behaviors indicative of anxiety and depression in the NTSR1 knockout mouse.

MEASUREMENTS AND RESULTS

NTSR1 knockouts had a lower percentage of sleep time spent in REM sleep in the dark phase and a larger diurnal variation in REM sleep duration than wild types under baseline conditions. Following sleep deprivation, NTSR1 knockouts exhibited more wake and less NREM rebound sleep. NTSR1 knockouts also showed increased anxious and despair behaviors.

CONCLUSIONS

Here we illustrate a link between expression of the Ntsr1 gene and sleep traits previously associated with a particular QTL. We also demonstrate a relationship between Ntsr1 and anxiety and despair behaviors. Given the considerable evidence that anxiety and depression are closely linked with abnormalities in sleep, the data presented here provide further evidence that neurotensin and Ntsr1 may be a component of a pathway involved in both sleep and mood disorders.

Sex Differences in Slow-wave Electroencephalographic Activity (SWA) in Adolescent Depression

Sleep disturbances, present in more than 90% of major depressive disorder (MDD) patients, are moderated by sex in adult MDD. In particular, slow-wave electroencephalographic activity (SWA; 0.5-4 Hz) accumulation is low and dissipation impaired. This SWA abnormality in depressed adult males does not change with age, suggesting that SWA abnormality appears at early ages. The present study evaluated sex differences in SWA in adolescents with MDD compared to healthy controls. We evaluated regularized sleep-wake schedules at home for 5-7 days, followed by two consecutive nights of sleep EEG recording. The study included 104 participants, 52 symptomatic and depressed subjects (MDD: 20 males and 32 females) and 52 healthy controls (HC: 20 males and 32 females), aged 13-18 years. SWA power and dissipation, and duration and latencies to each Non-Rapid Eye Movement (NREM) sleep period were calculated for each group. Results showed that SWA accumulation in the first NREM period was lower and its dissipation across the night more irregular in MDD males compared to HC males (P<0.009). By contrast, SWA was equivalent in MDD and HC females. In conclusion, as reported in adult MDD, the accumulation and dissipation of SWA was abnormal in depressed adolescents, but only in males. SWA abnormalities in adolescent MDD may relate to different depressive symptoms in females and males. These results underscore the need to develop sex-specific therapies to enhance and restore SWA in depressed adolescents.

R278995/CRA0450, a corticotropin-releasing factor (CRF(1)) receptor antagonist modulates REM sleep measures in rats: Implication for therapeutic indication

Abnormalities in the regulation of the hypothalamic stress hormone corticotropin-releasing factor (CRF) are thought to play a critical role in mood disorders. Consequently, CRF receptor antagonists have been proposed as potential novel therapeutic agents of these conditions. Sleep disturbance is common in depressed patients and changed sleep-wake architecture is considered as potential predictor or surrogate marker of response to treatment. The aim of our study was to characterise the effects of oral administration of the corticotropin-releasing factor CRF(1) receptor antagonist R278995/CRA0450 (3 and 10mg/kg) on sleep-wake organization and electroencephalographic (EEG) components in Sprague-Dawley rats, and to determine whether the changes observed in the sleep-EEG pattern resemble those seen with antidepressants. At 3mg/kg, R278995/CRA0450 produced minor changes in sleep behaviour, while an overall reduction in power spectra was observed during deep slow wave sleep. At 10mg/kg, R278995/CRA0450 consistently reduced rapid eye movement (REM) sleep (-75.4%) and increased the REM sleep onset latency (+67%, 92.1±4.9min for vehicle vs. 153.8±24min for R278995/CRA0450), in the absence of systematic changes in spectral EEG pattern, which are characteristic anti-depressant-like effects. These findings in rats indicate that the corticotropin-releasing factor CRF(1) receptor antagonist R278995/CRA0450 is centrally active under standard conditions as it inhibits REM sleep and promotes wakefulness. The characteristic changes found in the sleep EEG model further support the hypothesis that R278995/CRA0450 could exert a non-sedative, antidepressant-like action.

Predictors of sleep characteristics among women in southeast Texas

PURPOSE

This study examined psychological and sociodemographic predictors of self-reported sleep characteristics including sleep duration, quality, and perceived adequacy of sleep among Hispanic and non-Hispanic women of low socioeconomic status.

METHOD

Cross-sectional survey data were analyzed from 2,670 women ages 18 to 55 (74% Hispanic, 18% non-Hispanic White, 8% non-Hispanic Black) participating in a cancer prevention study in southeast Texas.

RESULTS

Women reported sleeping 7.1 hours per night on average; however, nearly 45% were short (≤6; 35.3%) or long (≥9; 9.5%) sleepers. Sleep quality was rated less than "good" for 43.7% of the total sample, and 22.5% reported adequate sleep "none" or "a little" of the time. Multivariable analyses identified different demographic and psychological predictors for the sleep characteristics; decreased sleep adequacy was associated with parity, depressive symptoms, stress, and anxiety (R(2) = 0.11); short sleep duration with age, education, and depressive symptoms (R(2) = 0.07); and poor sleep quality with ethnicity, marital and employment status, public housing accommodation, smoking status, income, acculturation, social desirability, depressive symptoms, stress, and anxiety (R(2) = 0.18). Separate analyses of the Hispanic subsample born in the United States versus elsewhere revealed differences in all sleep characteristics. In multivariable analyses, similar predictors of sleep quality and duration emerged, but only depressive symptoms, anxiety, and age were associated with sleep adequacy.

CONCLUSION

Women of lower socioeconomic groups and Hispanic ethnicity may suffer poor quality sleep. A complex and distinct array of factors are associated with sleep quality, duration, and adequacy. The relationship between sleep and health and the growing U.S. Hispanic population highlight the importance of this and future research.

Insomnia as predictor versus outcome of PTSD and depression among Iraq combat veterans

OBJECTIVES

The study conducted a longitudinal assessment of insomnia as an antecedent versus consequence of posttraumatic stress disorder (PTSD) and depression symptoms among combat veterans.

DESIGN

Two postdeployment time points were used in combination with structural equation modeling to examine the relative strength of two possible directions of prediction: insomnia as a predictor of psychological symptoms, and psychological symptoms as a predictor of insomnia. Participants were active duty soldiers (N = 659) in a brigade combat team who were assessed 4 months after their return from a 12-month deployment to Iraq, and then again eight months later.

RESULTS

Although both insomnia and psychological symptoms were associated at both time periods and across time periods, insomnia at 4 months postdeployment was a significant predictor of change in depression and PTSD symptoms at 12 months postdeployment, whereas depression and PTSD symptoms at 4 months postdeployment were not significant predictors of change in insomnia at 12 months postdeployment.

CONCLUSIONS

Results support the role of insomnia in the development of additional psychological problems and highlight the clinical implications for combat veterans, to include the importance of longitudinal assessment and monitoring of sleep disturbances, and the need for early intervention.

Poor sleep quality predicts deficient emotion information processing over time in early adolescence

STUDY OBJECTIVES

There is deepening understanding of the effects of sleep on emotional information processing. Emotion information processing is a key aspect of social competence, which undergoes important maturational and developmental changes in adolescence; however, most research in this area has focused on adults. Our aim was to test the links between sleep and emotion information processing during early adolescence.

DESIGN

Sleep and facial information processing were assessed objectively during 3 assessment waves, separated by 1-year lags.

SETTING

Data were obtained in natural environments-sleep was assessed in home settings, and facial information processing was assessed at school.

PARTICIPANTS

94 healthy children (53 girls, 41 boys), aged 10 years at Time 1.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Facial information processing was tested under neutral (gender identification) and emotional (emotional expression identification) conditions. Sleep was assessed in home settings using actigraphy for 7 nights at each assessment wave. Waking > 5 min was considered a night awakening. Using multilevel modeling, elevated night awakenings and decreased sleep efficiency significantly predicted poor performance only in the emotional information processing condition (e.g., b = -1.79, SD = 0.52, confidence interval: lower boundary = -2.82, upper boundary = -0.076, t(416.94) = -3.42, P = 0.001).

CONCLUSIONS

Poor sleep quality is associated with compromised emotional information processing during early adolescence, a sensitive period in socio-emotional development.

Acute sleep restriction effects on emotion responses in 30- to 36-month-old children

Early childhood is a period of dramatic change in sleep and emotion processing, as well as a time when disturbance in both domains are first detected. Although sleep is recognized as central in emotion processing and psychopathology, the great majority of experimental data have been collected in adults. We examined the effects of acute sleep restriction (nap deprivation) on toddlers' emotion expression. Ten healthy children (seven females; 30-36 months old) followed a strict sleep schedule (≥12.5 h time in bed per 24-h) for 5 days, before each of two randomly assigned afternoon emotion assessments following Nap and No-Nap conditions (resulting in an 11-day protocol). Children viewed emotion-eliciting pictures (five positive, three neutral, three negative) and completed puzzles (one solvable, one unsolvable). Children's faces were video-recorded, and emotion displays were coded. When sleep restricted, children displayed less confusion in response to neutral pictures, more negativity to neutral and negative pictures, and less positivity to positive pictures. Sleep restriction also resulted in a 34% reduction in positive emotion responses (solvable puzzle), as well as a 31% increase in negative emotion responses and a 39% decrease in confused responses (unsolvable puzzle). These findings suggest sleep is a key factor in how young children respond to their world. When sleep restricted, toddlers are neither able to take full advantage of positive experiences nor are they as adaptive in challenging contexts. If insufficient sleep consistently 'taxes' young children's emotion responses, they may not manage emotion regulation challenges effectively, potentially placing them at risk for future emotional/behavioral problems.

Correlates to sleepiness on night shift among male workers engaged in three-shift work in a chemical plant: its association with sleep practice and job stress

The purpose of this study was to examine the correlation of sleepiness during night shift (SNS) in male shiftworkers with nonpharmacological self-management (nPSM) practices to facilitate good day sleep, and also with job stress. Sleepiness on the job and possible correlates to SNS among 157 male shiftworkers in a rotating three-shift schedule at a chemical plant were cross-sectionally investigated using a self-administered questionnaire. Multivariate analyses revealed that SNS was positively associated with drinking alcoholic beverages before day sleep, but inversely associated with subjective health status, being of the evening type, abstaining from caffeine before day sleep, having a bath before day sleep, job control, reward from work, feeling suited to the job, and support from colleagues. SNS correlated with certain nPSM practices and also with possible modifiers of job stress. These findings provide clues to developing countermeasures against SNS among shiftworkers. The effects of nPSM practices and job stress management on their day sleep and SNS should be examined in detail.

Antidepressant effects of selective slow wave sleep deprivation in major depression: a high-density EEG investigation

Sleep deprivation can acutely reverse depressive symptoms in some patients with major depression. Because abnormalities in slow wave sleep are one of the most consistent biological markers of depression, it is plausible that the antidepressant effects of sleep deprivation are due to the effects on slow wave homeostasis. This study tested the prediction that selectively reducing slow waves during sleep (slow wave deprivation; SWD), without disrupting total sleep time, will lead to an acute reduction in depressive symptomatology. As part of a multi-night, cross-over design study, participants with major depression (non-medicated; n = 17) underwent baseline, SWD, and recovery sleep sessions, and were recorded with high-density EEG (hdEEG). During SWD, acoustic stimuli were played to suppress subsequent slow waves, without waking up the participant. The effects of SWD on depressive symptoms were assessed with both self-rated and researcher-administered scales. Participants experienced a significant decrease in depressive symptoms according to both self-rated (p = .007) and researcher-administered (p = .010) scales, while vigilance was unaffected. The reduction in depressive symptoms correlated with the overnight dissipation of fronto-central slow wave activity (SWA) on baseline sleep, the rebound in right frontal all-night SWA on recovery sleep, and the amount of REM sleep on the SWD night. In addition to highlighting the benefits of hdEEG in detecting regional changes in brain activity, these findings suggest that SWD may help to better understand the pathophysiology of depression and may be a useful tool for the neuromodulatory reversal of depressive symptomatology.

Relationship of morningness-eveningness questionnaire score to melatonin and sleep timing, body mass index and atypical depressive symptoms in peri- and post-menopausal women

Previous work shows a relationship between measures of morning or evening preference (e.g., morningness-eveningness questionnaire (MEQ) scores) and melatonin and sleep timing, body mass index (BMI) and mood. This study explores the relationship of these factors to atypical depression (ATD) symptoms, particularly increased appetite and hypersomnia, in depressed and non-depressed peri- and post-menopausal women. Participants were 19 normal control subjects and 10 depressed patients, 46-72 years of age. In a university hospital setting, we administered the MEQ and Structured Interview Guide for the Hamilton Depression Rating Scale, Seasonal Affective Disorders (SIGH-SAD version), which includes a measure of ATD, 3-5 weeks before obtaining nighttime polysomnography and overnight plasma melatonin in dim light (<30lx). Scores on SIGH-SAD appetite-related items were significantly correlated with MEQ, dim light melatonin onset (DLMO) time and midsleep time (MST); BMI was related to MST, sleep end time, phase-angle differences between sleep and melatonin timing, and appetite measures. Results suggest that relative to women with earlier DLMOs and MSTs, depressed peri- and post-menopausal women whose DLMOs and MSTs are phase-delayed may experience increases in appetite, hypersomnia, and BMI. These symptoms might be relieved by sleep or light manipulations that advance melatonin and sleep timing parameters.

Association of temperament with subjective sleep patterns

BACKGROUND

Emotional and cognitive functioning have been involved in insomnia etiology, and sleep disturbances are closely related to psychiatric disorders and personality traits. This study investigates the association of temperament with subjective sleep parameters.

METHODS

In this web-survey, 5129 subjects (25.3% males) completed the Combined Emotional and Affective Temperament Scale (CEATS), which assesses emotional (fear, anger, drive and control) and affective (e.g. cyclothymic, hyperthymic) temperaments. Subjects also answered questions regarding subjective sleep parameters, psychiatric diagnosis, psychotropic medication intake and cigarette smoking.

RESULTS

As control scores decreased, the later were the bed and the wake up time. Total sleep time was weakly associated with emotional temperaments. The higher the score of anger and the lower the score of control, the higher was the sleep-onset latency. As the anger score increased and the drive, fear and control scores decreased, the higher the number of nightly awakenings. The higher the drive and the control and the lower the anger scores, the better the sleep quality. For affective temperaments, depressives, labiles (related to ADHD) and cyclothymics (related to bipolar II disorders) go to bed and wake up later and have a worse profile regarding other sleep parameters. Hyperthymics and euthymics showed favorable sleep profiles.

LIMITATIONS

Sample included a significant number of subjects with psychiatric diseases and on psychotropic medication.

CONCLUSION

Dysregulated emotional activation (expressed as higher anger, and lower control and drive), as well as depressive, labile and cyclothymic affective temperaments were related to more dysfunctional sleep patterns.

Development and initial validation of the Iowa Sleep Disturbances Inventory

The Iowa Sleep Disturbances Inventory (ISDI) is a new measure of self-reported sleep difficulties, which was designed to help facilitate research on the overlap of sleep disturbances and psychopathology. This instrument was developed in two large student samples using principal factor analyses; the psychometric properties of the scales were then examined in three additional samples (students, psychiatric patients, sleep disorder patients). The ISDI consists of 11 specific scales (Nightmares, Initial Insomnia, Fatigue, Fragmented Sleep, Nonrestorative Sleep, Anxiety at Night, Light Sleep, Movement at Night, Sensations at Night, Excessive Sleep, Irregular Schedule) and 1 general scale (Daytime Disturbances). The structure of the ISDI generalizes across both patient and nonpatient samples. In addition, the ISDI scales are internally consistent, show good retest reliability, demonstrate convergent and discriminant validity with widely used measures of sleep disturbances, and display criterion validity in relation to psychiatric patient status and specific symptoms of depression and anxiety.

Thalamic dysfunction in schizophrenia suggested by whole-night deficits in slow and fast spindles

OBJECTIVE

Slow waves and sleep spindles are the two main oscillations occurring during non-REM sleep. While slow oscillations are primarily generated and modulated by the cortex, sleep spindles are initiated by the thalamic reticular nucleus and regulated by thalamo-reticular and thalamo-cortical circuits. In a recent high-density EEG study, the authors found that 18 medicated schizophrenia patients had reduced sleep spindles, compared with healthy and depressed subjects, during the first non-REM episode. In the present study, the authors investigated whether spindle deficits were present in a larger sample of schizophrenia patients, were consistent across the night, were related to antipsychotic medications, and were suggestive of impairments in specific neuronal circuits.

METHOD

Whole-night high-density EEG recordings were performed in 49 schizophrenia patients, 20 nonschizophrenia patients receiving antipsychotic medication, and 44 healthy subjects. In addition to sleep spindles, several parameters of slow waves were assessed.

RESULTS

Schizophrenia patients had whole-night deficits in spindle power (12-16 Hz) and in slow (12-14 Hz) and fast (14-16 Hz) spindle amplitude, duration, number, and integrated activity in the prefrontal, centroparietal, and temporal regions. Integrated spindle activity and spindle number had the largest effect sizes (effect size: ≥ 2.21). In contrast, no slow wave deficits were found in schizophrenia patients.

CONCLUSIONS

These results indicate that spindle deficits can be reliably established in schizophrenia, are stable across the night, are unlikely to be due to antipsychotic medications, and point to deficits in the thalamic reticular nucleus and thalamo-reticular circuits.

Napping promotes inter-session habituation to emotional stimuli

The effects of a daytime nap on inter-session habituation to aversive visual stimuli were investigated. Healthy young adult volunteers viewed repeated presentations of highly negative and emotionally neutral (but equally arousing) International Affective Picture System (IAPS) photographs during two afternoon sessions separated by 2.5h. Half of the photographs were shown at both sessions (Repeated Sets) and half differed between sessions (Novel Sets). For each stimulus presentation, evoked skin conductance response (SCR), heart-rate deceleration (HRD) and corrugator supercilii EMG response (EMG), were computed and range corrected using respective maximum session-1 responses. Following each presentation, subjects rated each photograph on dimensions of pleasantness and arousability. During the inter-session interval, Nap subjects had a 120-min polysomnographically monitored sleep opportunity, whereas Wake subjects watched a non-stimulating video. Nap and Wake subjects did not differ in their subjective ratings of photographs. However, for Repeated-Set photographs, Nap subjects demonstrated greater inter-session habituation in SCR and EMG but a trend toward lesser inter-session habituation in HRD. These group differences were absent for Novel-Set photographs. Group differences across all measures were greater for negative stimuli. Occurrence of SWS during the nap was associated with greater inter-session habituation of EMG whereas occurrence of REM was associated with lesser inter-session habituation of SCR to negative stimuli. Sleep may therefore promote emotional adjustment at the level of somatic responses. Physiological but not subjective inter-session habituation to aversive images was enhanced by a daytime nap.

Lucid dreaming and ventromedial versus dorsolateral prefrontal task performance

Activity in the prefrontal cortex may distinguish the meta-awareness experienced during lucid dreams from its absence in normal dreams. To examine a possible relationship between dream lucidity and prefrontal task performance, we carried out a prospective study in 28 high school students. Participants performed the Wisconsin Card Sort and Iowa Gambling tasks, then for 1 week kept dream journals and reported sleep quality and lucidity-related dream characteristics. Participants who exhibited a greater degree of lucidity performed significantly better on the task that engages the ventromedial prefrontal cortex (the Iowa Gambling Task), but degree of lucidity achieved did not distinguish performance on the task that engages the dorsolateral prefrontal cortex (the Wisconsin Card Sort Task), nor did it distinguish self-reported sleep quality or baseline characteristics. The association between performance on the Iowa Gambling Task and lucidity suggests a connection between lucid dreaming and ventromedial prefrontal function.

Clock genes at the heart of depression

The rhythms of life are ever pervasive, touching almost every aspect of our lives. We are finely tuned to the cycle of light and dark, so that we normally sleep during the night and are active during the day. Physiological rhythms are, however, not just slaves to the solar day, but are actually generated endogenously within the suprachiasmatic nuclei in the hypothalamus and are entrained via the retina. The circadian timing system is organized hierarchically with the suprachiasmatic nuclei providing neural and/or hormonal cues to the various organ systems, allowing them to express their own rhythmic physiological output. There is now a substantial body of evidence emerging that disruption of rhythmicity through altered sleep/wake patterns and exposure to light, or through endogenous disruption of key determinants of endogenous rhythms, can be detrimental to health. Circadian rhythm disturbances have long been associated with mood disorders, especially delayed sleep onset, and evidence is accumulating that alterations to the cellular timing system may underpin some aspects of the disorders. For example, mice carrying mutations in either Clock or per2 spend less time immobile in swim tests, which has been suggested as mimicking mania. In humans, single nucleotide polymorphisms in Clock and other clock genes have been associated with depression. With this increasing knowledge we may predict that new antidepressant drugs will emerge that, as a primary or secondary mechanism of action, target and correct abnormalities in the circadian timing system.

Prevalence of insomnia and its psychosocial correlates among college students in Hong Kong

OBJECTIVE

this study examined the prevalence of insomnia and its psychosocial correlates among college students in Hong Kong.

PARTICIPANTS

a total of 529 Hong Kong college students participated in the study.

METHODS

participants completed a self-reported questionnaire that included the Pittsburgh Sleep Quality Index (PSQI), the Revised Life Orientation Test, the Perceived Stress Scale, and the Beck Depression Inventory, and questions about sociodemographic and lifestyle factors. A PSQI global score equal to or greater than 5 indicated insomnia.

RESULTS

results indicated that 68.6% of the participants were insomniacs. Adjusted regression analyses revealed that optimism, stress, and depression significantly predicted insomnia (p < .01).

CONCLUSIONS

these results suggest that insomnia is very common among Hong Kong college students and associated with other psychosocial factors. This study provides preliminary data on sleep quality and risk factors for insomnia, which may be used to guide sleep hygiene promotion and intervention among college students.

Insomnia and depression: a multifaceted interplay

Historically, insomnia has been viewed as a symptom of depressive illness that is expected to resolve with adequate treatment of the depressive disorder. This article reviews the evidence that increasingly challenges this simplistic view and summarizes research demonstrating the multifaceted interplay between insomnia and depression. It discusses the prevalence, clinical significance, and time course of insomnia, distinguishing between poor sleep and an insomnia disorder. The article also discusses abnormalities in sleep architecture in major depressive disorder and theories about the pathways connecting sleep and depression. It concludes with a discussion of issues related to treatment, including the effects of antidepressants on sleep and new evidence of the utility of adding an insomnia-specific therapy for improved management of depressed patients with comorbid insomnia.

Algorithms for the assessment and management of insomnia in primary care

Insomnia is a leading cause of sleep disturbance in primary care practice affecting >30% of people in the United States and can result in psychological and physiological consequences. We aim for a focused discussion of some of the underpinnings of insomnia and practical tips for management (eg, algorithms). A PubMed search was conducted using English language papers between 1997-2007, with the terms "sleep," "insomnia"; "primary care" and "clinics"; "comorbid conditions"; "treatment" and "management." Sleep, psychiatric and medical disorders significantly affect sleep, causing patient suffering, potentially worsening of other disorders and increasing the use of primary care services. We provide an outline for practical assessment and treatment of insomnia in primary care, including the strengths and weaknesses of medications.

Circadian misalignment in major depressive disorder

It has been hypothesized that the circadian pacemaker plays a role in major depressive disorder (MDD). We sought to determine if misalignment between the timing of sleep and the pacemaker correlated with symptom severity in MDD. Depression severity correlated with circadian misalignment: the more delayed, the more severe the symptoms.

Narcolepsy and depression and the neurobiology of gammahydroxybutyrate

A voluminous literature describes the relationship between disturbed sleep and depression. The breakdown of sleep is one of the cardinal features of depression and often also heralds its onset. Frequent arousals, periods of wakefulness and a short sleep onset REM latency are typical polysomnographic features of depression. The short latency to REM sleep has been attributed to the combination of a monoaminergic deficiency and cholinergic supersensitivity and these irregularities have been proposed to form the biological basis of the disorder. A similar imbalance between monoaminergic and cholinergic neurotransmission has been found in narcolepsy, a condition in which frequent awakenings, periods of wakefulness and short sleep onset REM latencies are also characteristic findings during sleep. In many cases of narcolepsy, this imbalance appears to result from a deficiency of hypocretin but once established, whether in depression or narcolepsy, this disequilibrium sets the stage for the dissociation or premature appearance of REM sleep and for the dissociation of the motor inhibitory component of REM sleep or cataplexy. In the presence of this monoaminergic/cholinergic imbalance, gammahydroxybutyrate (GHB) may acutely further reduce the latency of REM sleep and induce cataplexy, in both patients with narcolepsy or depression. On the other hand, the repeated nocturnal application of GHB in patients with narcolepsy improves the continuity of sleep, prolongs the latency to REM sleep and prevents cataplexy. Evidence to date suggests that GHB may restore the normal balance between monoaminergic and cholinergic neurotransmission. As such, the repeated use of GHB at night and the stabilization of sleep over time makes GHB an effective treatment for narcolepsy and a potentially effective treatment for depression.

Early adverse rearing experiences alter sleep-wake patterns and plasma cortisol levels in juvenile rhesus monkeys

Monkeys separated from their mothers soon after birth and raised with peers display many disturbances in emotional behavior that are similar to human mood and anxiety disorders. In addition to emotional disturbances, both mood and anxiety disorders are often characterized by disruptions in normal sleep-wake cycles, a behavior that has not been well characterized in adversely reared non-human primates. Because polysomnographic measures are difficult to obtain in unrestrained monkeys we used 24-h actigraphy measures to assess probable sleep-wake patterns in juvenile nursery- and mother-reared rhesus macaques (Macaca mulatta, N=16) over several days in the home cage. In addition we assayed plasma cortisol in the morning, afternoon, and evening. Relative to mother-reared (MR) monkeys, actigraphic algorithms indicated that nursery-reared (NR) animals had shorter durations of nocturnal sleep, earlier morning waking, and longer periods of sleep during the active period, specifically in the mid morning. No shift in diurnal patterns of cortisol was observed, but NR animals displayed an overall elevation in cortisol. Finally a significant interaction was found between cortisol and actigraphic determination of sleep efficiency in the two groups. A strong positive relationship (r(2)>0.8) was found between mean cortisol levels and sleep efficiency for the MR monkeys, but a significant negative relationship was found between these same variables for the NR monkeys, indicating a fundamentally different relationship between waking cortisol and actigraphy patterns in these two groups.

Uncovering the genetic landscape for multiple sleep-wake traits

Despite decades of research in defining sleep-wake properties in mammals, little is known about the nature or identity of genes that regulate sleep, a fundamental behaviour that in humans occupies about one-third of the entire lifespan. While genome-wide association studies in humans and quantitative trait loci (QTL) analyses in mice have identified candidate genes for an increasing number of complex traits and genetic diseases, the resources and time-consuming process necessary for obtaining detailed quantitative data have made sleep seemingly intractable to similar large-scale genomic approaches. Here we describe analysis of 20 sleep-wake traits from 269 mice from a genetically segregating population that reveals 52 significant QTL representing a minimum of 20 genomic loci. While many (28) QTL affected a particular sleep-wake trait (e.g., amount of wake) across the full 24-hr day, other loci only affected a trait in the light or dark period while some loci had opposite effects on the trait during the light vs. dark. Analysis of a dataset for multiple sleep-wake traits led to previously undetected interactions (including the differential genetic control of number and duration of REM bouts), as well as possible shared genetic regulatory mechanisms for seemingly different unrelated sleep-wake traits (e.g., number of arousals and REM latency). Construction of a Bayesian network for sleep-wake traits and loci led to the identification of sub-networks of linkage not detectable in smaller data sets or limited single-trait analyses. For example, the network analyses revealed a novel chain of causal relationships between the chromosome 17@29cM QTL, total amount of wake, and duration of wake bouts in both light and dark periods that implies a mechanism whereby overall sleep need, mediated by this locus, in turn determines the length of each wake bout. Taken together, the present results reveal a complex genetic landscape underlying multiple sleep-wake traits and emphasize the need for a systems biology approach for elucidating the full extent of the genetic regulatory mechanisms of this complex and universal behavior.

Sleep disorders: causes, effects, and solutions

Until recently, sleep has been a mystery even to scientists. Research has defined sleep function and the effects of sleep deprivation. Sleep disorders are interrelated with medical and psychiatric illnesses. This article presents insomnia, jet lag, and shift work sleep disorders and reviews issues related to women's health and sleep. Pharmacologic and behavioral treatments for sleep conditions are explored.

Sleep in hospitalized medical patients, part 1: factors affecting sleep

BACKGROUND

Multiple factors lead to sleep disturbances in hospitalized medical patients. Inadequate sleep can lead to both psychological and physiological consequences.

METHODS

A PubMed search was conducted using the terms: ("sleep deprivation," "sleep," or "insomnia") and ("hospitalized," "inpatient," "critical illness," or "acute illness") to review the published data on the topic of sleep in hospitalized medical patients. The search was limited to English-language articles published between 1997 and 2008. Subsequent PubMed searches were performed to clarify the data described in the initial search, including the terms "hospital noise," "hospital environment," "obstructive sleep apnea," and "heart failure."

RESULTS

Few articles specifically addressed the topic of sleep in hospitalized medical patients. Data were limited to observational studies that included outcomes such as sleep complaints and staff logs of wakefulness and sleep. In Part 1, we review normal sleep architecture, and discuss how major medical disorders, the hospital environment, and medications can disrupt sleep during hospitalization. In Part 2, we will propose an evaluation and treatment algorithm to optimize sleep in hospitalized medical patients.

CONCLUSIONS

Hospitalization may severely disrupt sleep, which can worsen pain, cardiorespiratory status, and the psychiatric health of acutely ill patients. Like vital signs, the patient sleep quality reveals much about patients' overall well-being, and should be a routine part of medical evaluation.

The developmental decrease in REM sleep: the role of transmitters and electrical coupling

STUDY OBJECTIVES

This mini-review considers certain factors related to the developmental decrease in rapid eye movement (REM) sleep, which occurs in favor of additional waking time, and its relationship to developmental factors that may influence its potential role in brain development.

DESIGN

Specifically, we discuss some of the theories proposed for the occurrence of REM sleep and agree with the classic notion that REM sleep is, at the least, a mechanism that may play a role in the maturation of thalamocortical pathways. The developmental decrease in REM sleep occurs gradually from birth until close to puberty in the human, and in other mammals it is brief and coincides with eye and ear opening and the beginning of massive exogenous activation. Therefore, the purported role for REM sleep may change to involve a number of other functions with age.

MEASUREMENTS AND RESULTS

We describe recent findings showing that morphologic and physiologic properties as well as cholinergic, gamma amino-butyric acid, kainic acid, n-methyl-d-aspartic acid, noradrenergic, and serotonergic synaptic inputs to mesopontine cholinergic neurons, as well as the degree of electrical coupling between mostly noncholinergic mesopontine neurons and levels of the neuronal gap-junction protein connexin 36, change dramatically during this critical period in development. A novel mechanism for sleep-wake control based on well-known transmitter interactions, as well as electrical coupling, is described.

CONCLUSION

We hypothesize that a dysregulation of this process could result in life-long disturbances in arousal and REM sleep drive, leading to hypervigilance or hypovigilance such as that observed in a number of disorders that have a mostly postpubertal age of onset.