Polysomnographic findings in adolescents with major depression

Suprachiasmatic nucleus functional connectivity related to insomnia symptoms in adolescents with major depressive disorder

Background

Insomnia is a commonly seen symptom in adolescents with major depressive disorder (MDD). The suprachiasmatic nucleus (SCN), which is the circadian rhythm regulation center, plays a crucial role in the regulation of sleep-wake circulation. Nevertheless, how SCN function contributes to the exact neural mechanisms underlying the associations between insomnia and depressive symptoms has not been explored in adolescents. In the current study, we aimed to explore the relationship between SCN functional connectivity (FC) and insomnia symptoms in adolescents with MDD using a seed-based FC method.

Methods

In the current study, we recruited sixty-eight first-episode drug-naïve adolescents with MDD and classified them into high insomnia (MDD-HI) and low insomnia (MDD-LI) groups according to the sleep disturbance subscale of the Hamilton Depression Rating Scale (HAMD-S). Forty-three age/gender-matched healthy controls (HCs) were also recruited. SCN FC maps were generally for all subjects and compared among three groups using one-way ANOVA with age, gender and adjusted HAMD score as covariates. We used partial correlations to explore associations between altered FC and clinical symptoms, including sleep quality scores.

Results

Adolescents with MDD showed worse sleep quality, which positively correlated with the severity of depression. Compared to MDD-LI and HCs, MDD-HI adolescents demonstrated significantly decreased FC between the right SCN and bilateral precuneus, and there was no significant difference between the MDD-LI and HC groups. The HAMD-S scores were negatively correlated with bilateral SCN-precuneus connectivity, and the retardation factor score of HAMD was negatively correlated with right SCN-precuneus connectivity.

Conclusion

The altered FC between the SCN and precuneus may underline the neural mechanism of sleep-related symptoms in depressive adolescents and provide potential targets for personalized treatment strategies.

Abnormal sleep features in adolescent MDD and its potential in diagnosis and prediction of early efficacy

INTRODUCTION

Previous studies have shown that abnormal sleep architectures are the important indicator for diagnosing MDD and predicting the efficacy of antidepressants. However, few studies have focused specifically on adolescents.

OBJECTIVE

To explore the relationship between abnormal sleep features, including PSG parameters and scale evaluation, and the onset of adolescent MDD, as well as early SSRIs efficacy.

METHODS

102 adolescent MDD patients (age 12 to 19-year-old) and 41 similarly age-marched controls were recruited. Demographic data, the HAMD₂₄ and the PSQI scale assessment scores were collected at baseline, latter two were also collected at follow-up. Part of the participants underwent a minimum 7-d medication-free period, and two consecutive night polysomnography. In the follow-up study, MDD patients were treated with standardized SSRIs. Treatment response was assessed every two weeks.

RESULTS

MDD subjects' parental marital status, REM-sleep latency, N2, N2%, N3, REM-sleep duration, REM % showed significant differences at baseline. REM-sleep latency showed significant prediction of the onset of MDD. The HAMD₂₄ and PSQI scale assessment scores decreased over time in the follow-up study. Specifically, the sleep disorder factor score of HAMD₂₄, the scores of PSQI sleep latency, sleep disorder, sleep efficiency and total score showed significantly differences between responder and non-responder groups. PSQI baseline moderate group showed significant prediction of the early efficacy of SSRIs.

CONCLUSION

Abnormal sleep PSG parameters and self-evaluation could be predictors for the adolescent MDD onset and early SSRIs efficacy.

Subjective sleep problems and sleep hygiene among adolescents having depression: A case-control study

Sleep research has often focussed heavily on polysomnography while ignoring subjective sleep complaints of individuals, especially the young ones. Discordance has been seen between objective and subjective parameters of sleep among children and adolescents. There has been a trend towards worsening of sleep hygiene among adolescents, which may predispose to psychiatric disorders like depression. So, we compared the subjective sleep quality and sleep hygiene among depressed and normal adolescents. A sample of 31 depressed adolescents and 32 healthy controls were compared on sleep parameters using Adolescent Sleep Wake Scale (ASWS), Adolescent Sleep Hygiene Scale (ASHS) and School Sleep Habits Survey. Depressed adolescents were found to have significantly worse sleep quality [ASWS score 3.72 ± 0.952 vs 4.79 ± 0.552, p < 0.001], longer sleep onset latency [68.23 ± 62.98 vs 19.53 ± 19.48 minutes, p < 0.001], and shorter sleep duration [414.19 ± 110.78 vs 498.28 ± 56.86 minutes, p < 0.001]. Sleep quality significantly correlated with depression severity (measured on Children's Depression Rating Scale- revised), i.e., higher the severity of depression, poorer was the sleep quality (r = -0.605, p < 0.01). But sleep hygiene was statistically similar between the two groups [ASHS score 3.21 ± 0.60 vs 3.36 ± 0.51, p = 0.293], and was inadequate (< 3.8) among all adolescents irrespective of depression. Hence, despite the lack of evidence from objective sleep measures, there seem to be subjective sleep impairments among adolescents having depression. Future research needs to address the underlying etiological factors and causal directions for depression and sleep impairments among adolescents. Sleep hygiene education must be a part of broader primary prevention strategies for psychiatric disorders.

Sleep and slow-wave activity in depressed adolescent boys: a preliminary study

OBJECTIVE

Adolescence is a vulnerable period of life that is characterized by increasing incidence of depression. Sleep disturbance is one of the diagnostic symptoms of depressive disorder. Adolescence is also characterized by dramatic maturational changes in sleep and its regulation. The goal of this study was to assess sleep macroarchitecture and slow-wave activity (SWA) in depressed adolescent boys.

METHODS

Eight non-medicated adolescent boys meeting the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for depressive disorder and 10 age-matched healthy controls (average age 16.0 years) underwent polysomnography in their home environment for two consecutive nights. Sleep macroarchitecture, SWA, and SWA dissipation were assessed in all subjects.

RESULTS

Depressed boys showed a flattened pattern of SWA dissipation through the night. SWA power was lower during the first non-rapid eye movement (NREM) episode in the frontal derivation and higher during the third NREM episode in the central derivation in the group of depressed boys as compared to healthy boys. The SWA dissipation pattern correlated with the severity of depressive symptoms, and the correlation was strongest in the frontal derivation. In addition, total sleep time was shorter in patients as compared to the control group, but no other differences were found in the macroarchitecture of sleep.

CONCLUSION

Depression in adolescent boys is characterized by more evenly distributed SWA through the night as compared to healthy subjects, and we showed for the first time that this pattern of SWA distribution is associated with severity of depressive symptoms. These findings suggest that homeostatic regulation of sleep may be impaired in adolescent depression.

An investigation of the longitudinal relationship between sleep and depressed mood in developing teens

OBJECTIVE

The prospective, bidirectional relationship between sleep disturbance and depressed mood was assessed in a school-based sample of adolescents.

METHOD

One hundred and thirty-eight Australian adolescents (mean age time 1 =15.69, standard deviation =0.92; 64% male) completed questionnaires to assess sleep parameters and depressed mood, on two occasions over 1 year.

RESULTS

Cross-sectional associations were observed between depressed mood and sleep duration, as well as wakefulness in bed. Prospective analyses revealed depressed mood predicted less total sleep time on school nights and a longer latency to sleep onset on weekends 1 year later. There was no prospective support for sleep predicting later depressed mood.

CONCLUSION

Contrary to prediction, our results suggest in this case that depressed mood may act as a precursor to poor sleep rather than the converse.

A meta-analysis and model of the relationship between sleep and depression in adolescents: recommendations for future research and clinical practice

The purpose of this review was to quantify the strength of evidence for a directional relationship between sleep disturbance and depression in adolescents. A literature search was conducted to identify research investigating the relationship between sleep disturbance and depression in adolescent samples (12-20 y). Twenty-three studies were identified; 13 explored associations between depression and sleep disturbance; seven examined the prospective role of sleep disturbance in the development of depression; and three investigated the role of adolescent depression in the development of subsequent sleep disturbance. Average weighted mean differences in sleep/depression-related outcome variables were calculated between adolescents with depression, and non-clinical adolescents, or those in remission. Adolescents with depression experienced significantly more wakefulness in bed (sleep onset latency, wake after sleep onset, number of awakenings and sleep efficiency), lighter sleep (more stage 1), and reported more subjective sleep disturbance. Overall effect sizes from longitudinal and treatment studies suggest sleep disturbance acts as a precursor to the development of depression. At follow-up, depressed adolescents had significantly longer sleep onset, more wake after sleep onset, and lower sleep efficiency compared to adolescents who were non-clinical, or had undergone remission. Little support was found for a predictive role of depressive symptoms in the development of sleep disturbance. Based on these findings we propose a model to understand the development of depression from initial sleep disturbance, provide recommendations for clinicians and recommendations for future research.

Polysomnographic features of early-onset depression: a meta-analysis

BACKGROUND

Undiagnosed major depressive disorder (MDD) is associated with increased morbidity in children and adolescents. This study evaluated features of sleep macro- and microarchitecture assessed by polysomnography (PSG) as diagnostic markers for MDD in children and adolescents.

METHODS

MEDLINE, PSYCINFO, EMBASE and PUBMED were searched from their availability dates to March 1st, 2013. The literature search identified 932 abstracts of which 51 studies were retrieved and 28 were included in the analysis. Study design, features of sleep macro- and microarchitecture, demographic and clinical characteristics of study groups were extracted for each study.

RESULTS

There were modest differences on sleep macroarchitecture between children and adolescents with MDD and healthy controls. The most robust difference was found in sleep latency, 31% of adolescents with MDD had increased sleep latency. Age, suicidal ideation, suicidal behavior, and psychiatric comorbidities were significant predictors of sleep macroarchitecture. Modest differences were found for sleep microarchitecture, intrahemispheric and interhemispheric temporal coherence was decreased in a third of patients with MDD. Age was a significant predictor of sleep microarchitecture.

LIMITATIONS

This meta-analysis is limited by the small number of studies on sleep macroarchitecture in children with MDD and studies on sleep microarchitecture overall and by the heterogeneity in methodology between studies.

CONCLUSIONS

This synthetic review of the existing literature is among the largest to quantitatively assess impaired sleep as a diagnostic marker for MDD in children and adolescents. Knowledge of sleep macro- and microarchitecture in early-onset MDD may aid the clinician in developing a treatment strategy for MDD-related sleep symptoms in a subset of patients.

The regulation of sleep and arousal: Development and psychopathology

Throughout early development, a child spends more time asleep than in any waking activity. Yet, the specific role of sleep in brain maturation is a complete mystery. In this article, the developmental psychobiology of sleep regulation is conceptualized within the context of close links to the control of arousal, affect, and attention. The interactions among these systems are considered from an ontogenetic and evolutionary biological perspective. A model is proposed for the development of sleep and arousal regulation with the following major tenets:

1. Sleep and vigilance represent opponent processes in a larger system of arousal regulation.

2. The regulation of sleep, arousal, affect, and attention overlap in physiological, neuroanatomical, clinical, and developmental domains.

3. Complex interactions among these regulatory systems are modulated and integrated in regions of the prefrontal cortex (PFC).

4. Changes at the level of PFC underlie maturational shifts in the relative balance across these regulatory systems (such as decreases in the depth/length of sleep and increased capacity for vigilance and attention), which occur with normal development.

5. The effects of sleep deprivation (including alterations in attention, emotions, and goal-directed behaviors) also involve changes at the level of PFC integration across regulatory systems.

This model is then discussed in the context of developmental pathology in the control of affect and attention, with an emphasis on sleep changes in depression.

Sleep disturbances in children with psychiatric disorders

Sleep disturbances are highly prevalent among children with psychiatric disorders, making recognition and management of pediatric sleep disorders an important step in improving treatment outcome and preventing relapse of mental illness. This chapter will review the research data on the epidemiology, clinical presentation and treatment approaches for sleep disorders frequently seen in the context of common psychiatric conditions in children and adolescents. Readers will learn about interaction between sleep related problems and symptoms of Attention Deficit/Hyperactivity Disorder, Anxiety and Mood Disorders and Autism Spectrum Disorders, and about the impact of sleep loss and sleep fragmentation on the emotional and behavioral development in children.

Neurobiology of depression in children and adolescents

This article reviews classical and updated studies of the neurobiology of depressive disorders in children and adolescents. Most studies of childhood and adolescent depression and suicide have followed up the observations and methods used in studies in adults. These studies include neuroendocrine studies, which particularly look at the hypothalamic-pituitary-adrenal axis, the serotonergic system, peripheral blood and cerebrospinal fluid biologic markers, genetics, gene-environment interactions and sleep studies, and neuroimaging and postmortem studies, although in these areas the number of studies is limited.

Sleep microarchitecture in childhood and adolescent depression: temporal coherence

Previous work has indicated that low temporal coherence of ultradian sleep EEG rhythms is characteristic of depressed patients and women in particular. It may also be evident in depressed children and adolescents, although most published studies are limited in sample size. The present study evaluated temporal coherence of sleep EEG rhythms in 173 children and adolescents 8-17 years of age, including 97 who met criteria for major depressive disorder (MDD) and were symptomatic but unmedicated at the time of study and 76 healthy controls. Temporal coherence of all-night sleep EEG rhythms was evaluated on the second of two nights in the laboratory. Data were coded for diagnostic group, gender and age and subjected to MANOVAs. Temporal coherence was significantly lower in adolescents with MDD, compared to healthy controls. Findings were most robust for coherence between left and right beta and between delta and beta in both hemispheres. Both gender and age strongly influenced between-group differences, with the lowest temporal coherence among MDD girls, even in those under 13 years of age. In conclusion, early onset depression is associated with a reduction in synchronization of sleep EEG rhythms that shows a differential maturational course in boys and girls.

Sleep and depression in children and adolescents

There is considerable research evidence suggesting that sleep is biologically linked to mood disorders in adults. However, polysomographic and neuroendocrine studies in children and adolescents have not found consistent changes in sleep architecture paralleling adult major depression. This review provides a detailed description of sleep research that has been conducted in early-onset affective disorders, uncovers the potential limitations of the available data, and formulates future research directions in this important subject.

Pathways to adolescent health sleep regulation and behavior

There are several converging reasons to focus on sleep regulation in relation to healthy adolescent development: (a) Sleep appears to be particularly important during periods of brain maturation; (b) there are substantial biological and psychosocial changes in sleep and circadian regulation exist across pubertal development; (c) interactions between physical and psychosocial domains can lead to dramatic alterations in sleep patterns and habits during adolescence; (d) increasing evidence that many adolescents frequently obtain insufficient sleep exists; (e) there is mounting evidence that sleep deprivation has its greatest negative effects on the control of behavior, emotion, and attention, a regulatory interface that is critical in the development of social and academic competence, and psychiatric disorders; (f) the most obvious direct health consequences of insufficient sleep are high-risk behaviors associated with substance abuse and automobile accidents; (g) substantial evidence for bidirectional effects between sleep and behavioral/emotional regulation exists. Although the past decade has seen research progress in these areas, there continue to be major gaps in existing knowledge and a paucity of well-controlled studies to guide specific health policy decisions and recommendations regarding sleep in adolescence. In particular, there is need for improved understanding of the acute and chronic effects of inadequate sleep in adolescents, guidelines for defining adequate sleep in adolescents, and a better delineation of the links among sleep, behavior, and affect regulation. Finally, this paper briefly examines one specific application of this knowledge area regarding early starting times among some high schools.

Heterogeneity in EEG sleep findings in adolescent depression: unipolar versus bipolar clinical course

BACKGROUND

EEG sleep measures in child and adolescent subjects with depression have shown considerable variability regarding group differences between depressed and control subjects. This investigation was designed to assess whether some of the observed variability is related to undifferentiated unipolar and bipolar disorders in a sample that was reported previously.

METHODS

Twenty-eight adolescents who met criteria for unipolar major depression and 35 controls with no lifetime psychiatric disorder participated in a cross-sectional sleep polysomnography study. Approximately 7 years later, follow-up clinical evaluations were conducted in 94% of the original cohort. Clinical course during the interval period was assessed without knowledge of subjects' initial diagnostic and psychobiological status. Re-analysis of the original sleep data were performed with the added information of longitudinal clinical course.

RESULTS

Depressed subjects who had a unipolar course showed reduced REM latency, higher REM density, and more REM sleep (specifically in the early part of the night) compared with depressed adolescents who converted to bipolar disorder and controls who remained free from psychopathology at follow-up. In contrast to the unipolar group, depressed subjects who would later switch to bipolar disorder had demonstrated more stage 1 sleep and diminished stage 4 sleep.

CONCLUSIONS

These preliminary results indicate that some of the observed variability in EEG sleep measures in adolescent depression appear to be confounded by latent bipolar illness. The findings also suggest that sleep regulatory changes associated with unipolar versus bipolar mood disorders may be different.

Temporal coherence in ultradian sleep EEG rhythms in a never-depressed, high-risk cohort of female adolescents

BACKGROUND

Previous work has indicated that low temporal coherence of ultradian sleep electroencephalographic rhythms is characteristic of depressed patients and of depressed women, in particular. It may also be evident in one quarter of those at high risk, based on a family history of depression.

METHODS

The present study evaluated temporal coherence of sleep electroencephalographic rhythms in 41 adolescent girls with a maternal history of depression (high risk) and 40 healthy controls (low risk). The entire sample was followed clinically every 6 months for 2 years.

RESULTS

Temporal coherence was significantly lower among the high-risk girls than in controls. Regression analyses predicted group from coherence values and correctly classified 70% of the high-risk group with a false-positive rate of 5% among controls. Moreover, 54% of the high-risk girls were identified with extreme low coherence. On clinical follow up, 14 girls showed depressive symptoms, 9 in the high-risk group (22.5%) and 5 controls (12.2%). Six met DSM-IV criteria for first-episode major depressive disorder, five high-risk and one control. Most importantly, 41% of those identified as having the most abnormal coherence values either showed symptoms of depression or met diagnostic criteria upon follow up.

CONCLUSIONS

Low temporal coherence is evident in adolescent girls at high risk for depression. The more abnormal the coherence, the greater the risk of a first episode of major depressive disorder within 2 years of sleep study, approximately 10 times greater than in controls.

Premorbid polysomnographic signs in depressed adolescents: a reanalysis of EEG sleep after longitudinal follow-up in adulthood

BACKGROUND

This is a report of a clinical follow-up study (10-15 years later as young adults) of adolescent major depressives and normal control subjects. Polysomnographic data were obtained during the original study period when the subjects were adolescent (time 1). With clinical follow-up (time 2) assessments in hand, our objective was to ascertain whether there were any premorbid polysomnographic signs associated with depression during adolescence.

METHODS

Based upon initial (during adolescence) and follow-up clinical assessments (as adults), new subject groupings were generated: depression-free normal subjects and original normal subjects who experienced a depressive episode during the follow-up period (latent depressives). Suicidality and recurrence of depression were also examined. Multivariate analysis of covariance was used to analyze group differences in sleep measures and logistic regression for predicting three outcomes: lifetime depression, lifetime suicidality, and recurrence.

RESULTS

Comparison of the depression-free normal subjects, the latent depressives, and the original major depressives revealed significant differences for sleep latency and sleep period time. Comparing all lifetime depressives (original major depressives and the latent depressives) to depression-free normal subjects revealed significantly more stages 3 and 4 combined (ST34) sleep and greater sleep period times among the depressives. An analysis involving the presence or absence of suicidality revealed no overall significant differences between the groups. Comparison of the lifetime depressives grouped by nonrecurrent and recurrent depressive course to the depression-free normal subjects revealed significant difference for sleep period time. Using logistic regression, we found that a longer sleep latency and sleep period time significantly predicted lifetime depression. Gender, ST34 sleep, and an interaction term for ST34 sleep and REM latency significantly predicted lifetime suicidality.

CONCLUSIONS

There was evidence of premorbid sleep abnormalities during adolescence. A general pattern of sleep disruption around sleep onset and during the first 100 min of the sleep period and overall sleep was evident among the major and lifetime depressives, involving sleep latency (initial insomnia), sleep period time (hypersomnia), REM latency, and slow-wave sleep. This adds to the body of literature that highlights the importance of the first 100 min of the sleep period in depression.

Laboratory and performance-based measures of depression in children and adolescents

Reviews laboratory and performance-based measures for the assessment of symptoms and correlates of depression in children and adolescents. First, we briefly review limitations of self-report and other report measures of depression. Next, we describe four laboratory methods, including social interaction tasks, information-processing tasks, measures of psychological deficits and laboratory analogue designs, and sleep studies. We then summarize the specific depressive symptoms measured by each of these methods. Finally, we discuss issues of the validity and utility of these methods.

Sleep disorders in school-age children

This article on school age children reviews relevant issues in sleep physiology, the classification of sleep disorders, their clinical and laboratory assessment, some common sleep disorders, the sleep-epilepsy relationship, as well as the impact of daytime sleepiness on higher cortical functions.

Childhood and adolescent depression: a review of the past 10 years. Part I

OBJECTIVE

To qualitatively review the literature of the past decade covering the epidemiology, clinical characteristics, natural course, biology, and other correlates of early-onset major depressive disorder (MDD) and dysthymic disorder (DD).

METHOD

A computerized search for articles published during the past 10 years was made and selected studies are presented.

RESULTS

Early-onset MDD and DD are frequent, recurrent, and familial disorders that tend to continue into adulthood, and they are frequently accompanied by other psychiatric disorders. These disorders are usually associated with poor psychosocial and academic outcome and increased risk for substance abuse, bipolar disorder, and suicide. In addition, DD increases the risk for MDD. There is a secular increase in the prevalence of MDD, and it appears that MDD is occurring at an earlier age in successive cohorts. Several genetic, familial, demographic, psychosocial, cognitive, and biological correlates of onset and course of early-onset depression have been identified. Few studies, however, have examined the combined effects of these correlates.

CONCLUSIONS

Considerable advances have been made in our knowledge of early-onset depression. Nevertheless, further research is needed in understanding the pathogenesis of childhood mood disorders. Toward this end, studies aimed at elucidating mechanisms and interrelationships among the different domains of risk factors are needed.

The relationship between longitudinal clinical course and sleep and cortisol changes in adolescent depression

This study examined the relationship between longitudinal clinical course and sleep and cortisol findings in adolescent unipolar major depressive disorder (MDD). Subjects were 28 adolescents (15.4 +/- 1.3 years) systematically diagnosed with unipolar MDD and 35 group-matched normal controls who participated in EEG sleep and neuroendocrine studies. Follow-up clinical assessments were conducted 7.0 +/- 0.5 years later in 94% of the original cohort. Although initial group comparisons failed to show significant differences in biologic measures, analyses incorporating clinical follow-up reveal that changes in sleep and cortisol measures are associated with differential longitudinal course. Normal controls who would develop depression after the biologic studies had shown significantly higher density of rapid eye movements (REM) and a trend for reduced REM latency compared to controls with no psychiatric disorder at follow-up. Depressed subjects with a recurrent unipolar course showed a trend towards elevated plasma cortisol near sleep onset compared to MDD subjects with no further episodes during the follow-up interval.

Sleep onset abnormalities in depressed adolescents

Sleep measures were obtained in 16 depressed and 21 control adolescents following 1 week of adherence to a uniformly imposed and strictly enforced sleep/wake schedule. Three nights of baseline electroencephalographic (EEG) sleep on the same 10:00 PM to 7:00 AM schedule revealed prolonged sleep latency and reduced rapid eye movement (REM) latency in the depressed adolescents. Following baseline measures, sleep was restricted for 2 nights (10:00 PM-4:00 AM) and measures of recovery sleep were obtained showing further sleep latency differences. There was no evidence for delta sleep changes or sleep continuity differences in depressed adolescents. These results suggest that control over sleep/wake schedules is an important methodological issue in adolescent sleep studies. Furthermore, the findings are consistent with a larger body of evidence indicating that dysregulation near sleep onset represents a primary psychobiological change in early-onset depression.

Electroencephalographic sleep abnormalities in depressed children: a hypothesis

Although most studies on sleep in child and adolescent depression have indicated that sleep is relatively unaffected, abnormalities have been found. We hypothesized that discrepancies occur because family history of depression and sleep abnormalities in a parent have not been taken into account. In a group of parents and offspring with a family history of depression, 57% of parents had evidence of abnormal sleep. Sleep continuity and sleep architecture were correlated, and the magnitude of these correlations increased between parents with abnormal sleep and their offspring. Abnormal sleep may be expressed at a younger age when there is familial evidence for depression and abnormal sleep in a parent.

Electroencephalographic sleep measures in prepubertal depression

Two nights of electroencephalographic (EEG) sleep recording were performed in a group of prepubertal subjects with major depressive disorder (MDD) (n = 36, mean age = 10.4, SD = 1.5) and age-matched normal control children (n = 18, mean age = 10.1, SD = 1.6). All subjects were medically healthy and free of medications at the time of the study. There were no significant group differences for any major sleep variable after the initial adaptation night in this study. One subgroup of MDD subjects (n = 8) showed reduced REM latency on both recording nights, decreased stage 4 sleep, and increased REM time; this subgroup had significantly higher severity scores for depression but did not otherwise appear to be clinically distinct from the rest of the MDD subjects. Overall, the results indicate that the EEG sleep changes associated with depression in adults occurred less frequently in prepubertal MDD subjects.