EEG sleep in primary depression. A longitudinal placebo study

Resting-state EEG as a potential indicator to predict sleep quality in depressive patients

OBJECTIVES

To investigate the changes in sleep quality, heart rate variability (HRV) and resting-state electroencephalogram (rsEEG) in patients with major depressive disorder (MDD), and to explore whether HRV and rsEEG may be served as more convenient tools to assess sleep quality in MDD patients.

METHOD

We included a total of 91 subjects (46 healthy controls and 45 MDD patients) and compared their sleep quality, HRV and power spectra of rsEEG. Correlation analyses were conducted to discuss the relationship between HRV and seven factors of PSQI. Multiple linear regression model was used to examine whether absolute band power could predict sleep quality in MDD patients.

RESULTS

We found higher PSQI scores and lower levels of HRV in depressive individuals compared with healthy controls. In MDD patients, sleep latency was negatively correlated with RMSSD and HF. Delta, theta, and alpha band power of rsEEG were higher in MDD patients. Regression analyses showed delta band power of TP8, as well as theta, alpha band power of AF3 predicts PSQI score of MDD patients.

CONCLUSIONS

The findings of our study show that some aspects of sleep problems had negative correlations with parasympathetic activity and the regression model supports that the band power of rsEEG may be used as a potential indicator to evaluate the sleep quality in MDD patients.

SIGNIFICANCE

Cortical hyperarousal may be one of the reasons leading to poor sleep quality of MDD patients. And resting-state EEG can be used as a potential indicator for clinical assessment of MDD patients' sleep quality.

Inflammation Models of Depression in Rodents: Relevance to Psychotropic Drug Discovery

Inflammation and depression are closely inter-related; inflammation induces symptoms of depression and, conversely, depressed mood and stress favor an inflammatory phenotype. The mechanisms that mediate the ability of inflammation to induce symptoms of depression are intensively studied at the preclinical level. This review discusses how it has been possible to build animal models of inflammation-induced depression based on clinical data and to explore critical mechanisms downstream of inflammation. Namely, we focus on the ability of inflammation to increase the activity of the tryptophan-degrading enzyme, indoleamine 2,3 dioxygenase, which leads to the production of kynurenine and downstream neuroactive metabolites. By acting on glutamatergic neurotransmission, these neuroactive metabolites play a key role in the development of depression-like behaviors. An important outcome of the preclinical research on inflammation-induced depression is the identification of potential novel targets for antidepressant treatments, which include targeting the kynurenine system and production of downstream metabolites, altering transport of kynurenine into the brain, and modulating glutamatergic transmission.

Developmental changes in sleep and their relationships to psychiatric illnesses

PURPOSE OF REVIEW

Sleep undergoes major changes during development. Its relationship to the complex process of maturation in health and disease has recently received increased attention. This review aims to highlight the recent literature examining the interplay of altered sleep, brain development and emerging psychiatric illnesses in children and adolescents.

RECENT FINDINGS

In addition to a temporal relationship of sleep disturbances preceding the onset of psychiatric illnesses, a bi-directional interaction of altered sleep and symptom severity has increasingly been shown. Sleep architecture shows drastic age-dependent alterations on a structural level during the first 2 decades of life. However, findings regarding disease-specific patterns have remained inconsistent. On a functional level, recent evidence about sleep electroencephalographic characteristics points to a close relationship between slow waves, reflecting the depth of sleep, and cortical plasticity.

SUMMARY

Sleep provides a rich source of information to gain insight into both the healthy and disturbed processes of brain function and maturation. Emerging data suggest that the investigation of slow wave activity is a novel and promising tool for monitoring both of these processes. It is important to understand when and how deviations from typical developmental sleep alterations occur in order to improve prevention and early treatment of disorders affecting a substantial number of children and adolescents.

Sleep Disturbances in Pediatric Depression

Depressive illness beginning early in life can have serious developmental and functional consequences. Therefore, understanding its etiology and pathophysiology during this developmental stage is critical for developing effective prevention and intervention strategies. There is considerable evidence of sleep alterations in adult major depressive disorder. However, studies in children and adolescents have not found consistent changes in sleep architecture paralleling adult depression. This review article summarizes sleep polysomnography research in early-onset depression, highlighting the factors associated with variable findings across studies. In addition, potential avenues for future research will be suggested in order to develop more comprehensive theoretical models and interventions for pediatric depression.

Wake and sleep EEG provide biomarkers in depression

Both wake and sleep electroencephalogram (EEG) provide biomarkers of depression and antidepressive therapy, respectively. For a long time it is known that EEG activity is altered by drugs. Quantitative EEG analysis helps to delineate effects of antidepressants on brain activity. Cordance is an EEG measure with a superior correlation with regional brain perfusion. Prefrontal quantitative EEG cordance appears to be a predictor of the response to antidepressants. Sleep EEG shows characteristic changes in depression as impaired sleep continuity, desinhibition of REM sleep and changes of nonREM sleep. Elevated REM density (a measure for frequency of rapid eye movements) characterizes an endophenotype in family studies of depression. REM-sleep changes including a more distinct REM rebound after sleep deprivation are found in animal models of depression. Most antidepressants suppress REM sleep in depressed patients, normal controls and laboratory animals. REM suppression appears to be a distinct, but not an absolute requirement for antidepressive effects of a compound. Sleep-EEG variables like REM latency or certain clusters of variables were shown to predict the response to the treatment with a certain antidepressant or even the course of the disorder for several years. Some of these predictive sleep-EEG markers of the longterm course of depression appear to be closely related to hypothalamo-pituitary-adrenocortical system activity.

Comorbidity of insomnia and depression

During the last decade, several studies have shown that insomnia, rather than a symptom of depression, could be a medical condition on its own, showing high comorbidity with depression. Epidemiological research indicates that insomnia could lead to depression and/or that common causalities underlie the two disorders. Neurobiological and sleep EEG studies suggest that a heightened level of arousal may play a common role in both conditions and that signs of REM sleep disinhibition may appear in individuals prone to depression. The effects of antidepressant drugs on non-REM and REM sleep are discussed in relation to their use in insomnia comorbid with depression. Empirical treatment approaches are behavioral management of sleep combined with prescription of a sedative antidepressant alone, co-prescription of two antidepressants, or of an antidepressant with a hypnotic drug.

The neurochemistry of waking and sleeping mental activity: the disinhibition-dopamine hypothesis

This paper describes a hypothesis related to the neurochemical background of sleep-waking mental activity which, although associated with subcortical structures, is principally generated in the cerebral cortex. Acetylcholine, which mainly activates cortical neurons, is released at the maximal rate during waking and rapid eye movement (REM) sleep dreaming stage. Its importance in mental functioning is well-known. However, brainstem-generated monoamines, which mainly inhibit cortical neurons, are released during waking. Both kinds of influences contribute to the organized mentation of waking. During slow wave sleep, these two types of influence decrease in intensity but maintain a sufficiently high level to allow mental activity involving fairly abstract pseudo-thoughts, a mode of activity modelled on the diurnal pattern of which it is a poor reply. During REM sleep, the monoaminergic neurons become silent except for the dopaminergic ones. This results in a large disinhibition and the maintained dopamine influence may be involved in the familiar psychotic-like mental activity of dreaming. Indeed, in this original activation-disinhibition state, the increase of dopamine influence at the prefrontal cortex level could explain the almost total absence of negative symptoms of schizophrenia during dreaming, while an increase in the nucleus accumbens is possibly responsible for hallucinations and delusions, which are regular features of mentation during this sleep stage.

Does obstructive sleep apnea confound sleep architecture findings in subjects with depressive symptoms?

BACKGROUND

Compared with normal subjects, depressed patients have shorter rapid eye movement sleep latency (REML), increased REM and decreased slow wave sleep as a percentage of total sleep time (REM%, SWS%), and longer sleep latency (SL). Obstructive sleep apnea (OSA) patients experience longer REML, decreased REM% and SWS%, and shorter SL. We examined the interplay of depressive symptoms, OSA, and sleep architecture.

METHODS

Subjects (n = 106) were studied with polysomnography. OSA was defined as a Respiratory Disturbance Index > or = 15. Subjects were divided into Hi/Lo groups using a Center for Epidemiological Studies-Depression (CES-D) score of 16.

RESULTS

OSA patients had shorter SL than non-OSA patients (14.5 vs. 26.8 min, p <.001); Hi CES-D subjects showed a trend toward longer SL than Lo CES-D subjects (23.7 vs. 17.5 min, p =.079). Significant OSA x CES-D interactions emerged, however, for REM% (p =.040) and SL (p =.002): OSA/Hi CES-D subjects had higher REM% than OSA/Lo CES-D subjects (19.3% vs. 14.3%, p =.021); non-OSA/Hi CES-D subjects had SL (35.3 min) 2-3 times as long as other subjects (p =.002-.012).

CONCLUSIONS

Because of the high prevalence of OSA and depression, findings suggest that OSA must be considered in studies of mood and sleep architecture. Conversely, depressive symptoms must be considered in studies of OSA and sleep architecture.

Self-report and polysomnographic measures of sleep in women with irritable bowel syndrome

BACKGROUND

Women who report chronic gastrointestinal symptoms compatible with a diagnosis of irritable bowel syndrome (IBS) frequently report sleep disturbances.

OBJECTIVES

The purposes of this study were to (a) compare self-reported and polysomnographic indicators of sleep quality in women with IBS symptoms (IBS-SX, n= 16) and controls (n= 16); (b) examine the relationship between the indicators of sleep quality; and (c) determine the relationship between sleep indicators and psychological distress.

METHOD

The women slept in a laboratory for 2 consecutive nights. Polysomnographic measurements were recorded during sleep, and a sleep questionnaire was completed upon awakening each morning. Psychological distress was measured with the Symptom Checklist-90-R during the initial interview.

RESULTS

Women in the IBS-SX group reported significantly greater numbers of awakenings during sleep (p = .008) and had a longer latency to REM sleep (p = .04) than did the controls. Self-reported and polysomnographic indicators were more highly correlated in the control group than in the IBS-SX group. In the IBS-SX group, the greater the psychological distress, the less alert (rs = .419) and rested (rs = .564) the women felt in the morning and the more time the women spent in stages 3 and 4 sleep (rs = .479) and less in stage 2 (rs = -.447) and REM (rs = -.414) sleep. In the control group, psychological distress was not significantly associated with self-reported measures but was significantly associated with the number of awakenings (rs = .506) and time in stages 3 and 4 sleep (rs = -.677).

CONCLUSIONS

Although the women in the IBS-SX group reported significantly more awakenings, the weak relationship between self-reported and polysomnographic indicators suggests that clinicians must keep in mind that further assessments may be necessary.

Sleep cluster arousal analysis and treatment response to heterocyclic antidepressants in patients with major depression

BACKGROUND

A close link between sleep normalisation and antidepressant response in depressed patients has been reported. We attempt to separate early antidepressant treatment responders from nonresponders by the use of sleep EEG recordings.

METHODS

Sleep EEG recordings were performed in 20 inpatients with a unipolar major depressive disorder during the first and third week of treatment with heterocyclic antidepressants. Acute treatment polygraphic measures with microarousal analysis were used to predict response. Response was defined as a minimum reduction of > or = 30% in the v. Zerssen Depression Scale after 3 weeks.

RESULTS

Compared to the 11 nonresponders, the 9 responders initially showed a highly significant increase of arousals during sleep quantified with the cluster disturbed sleep (CDS), whereas the classical sleep parameters (REM, stage I-IV) had no predictive value.

CONCLUSIONS

The validity of our results is limited by the small number of patients and the lacking randomised assignment. Nevertheless the results are still interesting. Because the CDS clearly separated responders from nonresponders at treatment onset. This could be due to a different reagibility of the catecholaminergic system. The data indicate that the CDS can be helpful for the prediction of early antidepressant treatment response.

Controlled comparison of electrophysiological sleep in families of probands with unipolar depression

OBJECTIVE

This study presents polysomnographic data and psychiatric history for parents and siblings of probands with unipolar depression and short REM latency, probands with unipolar depression and normal REM latency, and normal comparison probands.

METHOD

Parents and adult siblings (N = 252) of probands (N = 64) were evaluated for lifetime history of psychiatric disorders and were studied in the sleep laboratory for 3 nights.

RESULTS

REM latency predicted lifetime history of major depression. Short REM latency was also associated with slow wave sleep deficits. Rate of short REM latency in relatives of depressed probands with short REM latency quadrupled the rate in relatives of both depressed probands with normal REM latency and normal probands. Lifetime risk of depression was almost twice as high in relatives of depressed probands with short REM latency as in relatives of depressed probands with normal REM latency.

CONCLUSIONS

Short REM latency and slow wave sleep deficits are familial. Short REM latency is associated with increased risk of major depression beyond the familial risk associated with a depressed proband. Polysomnographic abnormalities also occurred in unaffected relatives. Although the data can be considered only suggestive, these findings indicate that polysomnographic abnormalities may precede the clinical expression of depression and may be useful in identifying those at highest risk for the illness.

Identifying an abnormal electroencephalographic sleep profile to characterize major depressive disorder

There is little agreement as to the best definition of a categorically abnormal electroencephalographic (EEG) sleep profile to characterize major depressive disorder. Therefore, a series of classification, replication, and validation analyses were conducted to identify such a profile. The EEG sleep studies of healthy controls (n = 44), depressed inpatients (n = 44), and depressed outpatients (n = 181) were utilized, including subgroups of patients studied both before and after nonpharmacologic treatment with either cognitive behavior therapy (CBT) or interpersonal psychotherapy (IPT). A discriminant index score (based on reduced REM latency, increased REM density, and decreased sleep efficiency) was found to: 1) reliably discriminate between depressed inpatients, depressed outpatients, and controls; 2) show good test-retest reliability; and 3) identify a subset of depressed outpatients who were older, manifested a broader array of EEG sleep disturbances, and were less responsive to CBT or IPT. Posttreatment studies of patients indicated that normal sleep profiles were relatively stable, whereas abnormal profiles tended to normalize. These findings provide an empirically validated method that may improve the applicability, efficiency, and prognostic utility of EEG sleep studies of depressed patients.

Effect of pharmacologic treatments on the sleep of depressed patients

Antidepressant drugs produce striking effects on sleep architecture that are best understood in terms of their interactions with the monoamine pathways controlling sleep and wakefulness. Many different antidepressant drugs, including tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), and selective 5-hydroxytryptamine (5-HT; serotonin) reuptake inhibitors (SSRIs), decrease rapid eye movement (REM) sleep. The reduction in REM sleep produced by antidepressants may be an important part of their mechanism of action; however, the ability of new antidepressant compounds, such as nefazodone and moclobemide, to increase REM sleep throws doubt on this suggestion. The effects of antidepressants on slow-wave sleep (SWS) are quite diverse; in general, antidepressants having significant 5-HT2A/2C receptor antagonist properties increase SWS, whereas other drugs, such as SSRIs or MAOIs, either lower SWS or produce no change. Sleep continuity is improved acutely following administration of antidepressants with sedating properties such as certain TCAs, trazodone, and mianserin. Some nonsedating drugs (ritanserin and nefazodone) also improve sleep continuity measures, possibly through 5-HT2A/2C receptor blockade.

Latency to rapid eye movement sleep as a predictor of treatment response to fluoxetine and placebo in nonpsychotic depressed outpatients

Fluoxetine and placebo were compared in 89 outpatients with major depression with (n = 45) or without (n = 44) a reduced or shortened rapid eye movement latency (SREML) (< or = 65 minutes) to determine whether rapid eye movement latency (REML) predicted placebo and/or antidepressant response. Men and women were stratified based on polysomnographic recordings and then randomly assigned to receive double-blind fluoxetine (20 mg/day) or placebo for 8 weeks after a 2-week, single-blind, placebo lead-in period. Fluoxetine-treated patients demonstrated a significantly greater reduction in the Hamilton Rating Scale for Depression total score and a significantly greater response rate than placebo-treated patients in both the SREML and the combined strata. Treatment differences in the non-SREML stratum were not statistically significant. Results supported REML as a predictor of placebo nonresponse but did not predict a differential fluoxetine response in patients with SREML compared with patients without SREML.

Symposium: Normal and abnormal REM sleep regulation: REM sleep in depression-an overview

Abnormalities of REM sleep, i.e. shortening of REM latency, lengthening of the duration of the first REM period and heightening of REM density, which are frequently observed in patients with a major depressive disorder (MDD), have attracted considerable interest. Initial hopes that these aberrant patterns of sleep constitute specific markers for the primary/endogenous sub-type of depression have not been fulfilled. The specificity of REM sleep disinhibition for depression in comparison with other psychopathological groups is challenged as well. Demographic variables like age and sex exert strong influences on sleep physiology and must be controlled when searching for specific markers of depressed sleep. It is still an open question whether abnormalities of sleep are state- or trait-markers of depression. Beyond baseline studies, the cholinergic REM induction test (CRIT) indicated a heightened responsitivity of the REM sleep system to cholinergic challenge in depression compared with healthy controls and other psychopathological groups, with the exception of schizophrenia. A special role for REM sleep in depression is supported by the well-known REM sleep suppressing effect of most antidepressants. The antidepressant effect of selective REM deprivation by awakenings stresses the importance of mechanisms involved in REM sleep regulation for the understanding of the pathophysiology of depressive disorders. The positive effect of total sleep deprivation on depressive mood which can be reversed by daytime naps, furthermore emphasizes relationships between sleep and depression. Experimental evidence as described above instigated several theories like the REM deprivation hypothesis, the 2-process model and the reciprocal interaction model of nonREM-REM sleep regulation to explain the deviant sleep pattern of depression. The different models will be discussed with reference to empirical data gathered in the field.

Prospective assessment of electroencephalographic sleep in remitted major depression

We studied 29 patients with major depression before treatment and then followed these patients prospectively with monthly electroencephalographic (EEG) sleep assessments after successful treatment. Most EEG sleep measures demonstrated no change from the episode throughout a prolonged period of clinical remission. When there was evidence of a change in EEG sleep measures, the effect was modest and due to only a small subset of patients. These findings contribute to the accumulating evidence that selected EEG sleep measures appear to be trait-like and may be useful in identifying individuals at risk for major depression.

Sleep EEG and amitryptiline treatment in depressed inpatients

We studied the baseline sleep electroencephalogram (EEG) variables and treatment-related sleep changes after 35-46 days of amitryptiline treatment (AMI) in a group of 18 depressed inpatients, mostly suffering from a major depressive disorder endogenous subtype (according to the Research Diagnostic Criteria, RDC), with a short rapid eye movement (REM) latency. The aim of the study was to identify potential sleep "predictors" of clinical response to AMI as well as short-term sleep changes associated with alleviation of depression. Clinical response to the drug was defined as a reduction of more than 50% of the Hamilton Rating Score for Depression (HRSD). Eleven men and 7 women, 25-68 years old, were included in the study. Their sleep was recorded at baseline and after an average of 39 +/- 4 days of AMI treatment, at a mean daily dose of 165 +/- 35 mg. The comparison of responders (n = 9) and nonresponders (n = 9) with Wilcoxon's test showed that responders (1) were more severely depressed at baseline, and (2) had less stage 4 sleep. A discriminant function using baseline HRSD, stage 4 and the number of stage shifts allowed for discrimination between responders and nonresponders with a 100% hit rate. Antidepressant treatment had, however, no differential effect on sleep parameters in the two response groups.

Reduced rapid eye movement sleep latency in patients with Parkinson's disease

Rapid eye movement (REM) sleep latency (time from sleep onset to the first REM episode) was measured in 39 patients with idiopathic Parkinson's disease. Reduced REM sleep latency (less than or equal to 65.0 min) was found in a high proportion of patients (69%). Since reduced REM sleep latency may be a trait-like abnormality relatively specific to primary depression, we evaluated this parameter in two groups of parkinsonian patients: depressed (16 patients) and non-depressed (23 patients). Its incidence was significantly higher in depressed patients with Parkinson's disease.

Biology of depression

Research over the past three decades has led to a greater understanding of the biologic basis of depression. Observations that certain medications could improve or worsen mood led to the development of hypotheses describing the possible role of specific neurotransmitters in the brain in depression. Modifications of these original hypotheses focused on altered receptor function, failures in the regulation of neurotransmitter systems, and interactions of the monoamines with cholinergic systems. Strategies using endocrinologic measurements in the evaluation of the depressed patient have provided researchers with new clues regarding disordered neuroendocrine function in depression and clinicians with new tests to aid in diagnosis and management. Moreover, the development of standardized sleep EEG methodology has proven useful for the identification of characteristic sleep abnormalities in depression. Although there are many methodologic and clinical problems still to be resolved, the use of biological markers in the assessment of the depressed patient is increasing, and is likely to be of significant importance in the future. Finally, recent advances in molecular genetics hold promise for further advances in our understanding of the inheritance and biochemistry of depression.

Placebo response rates in psychotic and nonpsychotic depression

The authors reanalyzed data from two earlier studies that used double-blind placebo-controlled formats to study the efficacy of amitriptyline. Using a 14-day drug-free 'wash-out' period, they found that the placebo response rates were 0% for psychotic depressives and 13.3% for nonpsychotic depressives. Amitriptyline was significantly superior to placebo for both psychotic (P less than or equal to 0.05) and nonpsychotic (P less than or equal to 0.05) depressed patients.

Risk factors in families of unipolar depression. I. Psychiatric illness and reduced REM latency

In this report, we present data documenting the incidence of reduced REM latency and the lifetime prevalence of psychiatric illness in the parents and siblings of early onset unipolar depressed probands. The prevalence of psychiatric illness (49.3%), especially affective disorders (34.3%), was very high among these relatives. Reduced REM latency in the family members of reduced REM latency probands showed a concordance rate of 70.6% regardless of psychiatric history. The relative risk for unipolar depression among relatives with reduced REM latency was almost three times greater than for relatives with nonreduced REM latency.

Which endogenous depressive symptoms relate to REM latency reduction?

In most research dealing with biological abnormalities in depression, the clinical diagnosis of depression is made and the occurrence of a biological abnormality, for example, reduced REM latency, is documented. In this study, that design was reversed; REM latency was used as a grouping variable to assess empirically the "biological" priority of Research Diagnostic Criteria endogenous symptoms. We found that terminal insomnia, pervasive anhedonia, unreactive mood, and appetite loss were most likely to discriminate among "reduced" and "nonreduced" REM latency depressions at various threshold values. Contrary to expectation, diurnal mood variation was found equivalently in all categories of REM latency studied. Implications for clinical decision making based on endogenous symptoms are discussed.

Aspects of short REM latency in affective states: a revisit

Electroencephalographic (EEG) sleep changes in affective disorders have been characterized by sleep continuity, slow wave sleep, and rapid eye movement (REM) abnormalities. The most commonly cited feature, however, has been shortened REM latency. Because the diagnostic and prognostic significance of shortened REM latency has been debated, this issue was reexamined in a group of 186 psychotic and nonpsychotic depressed inpatients and outpatients. The analyses suggest an increased frequency of sleep onset REM periods in psychotic depression and in elderly depressed patients (psychotic or nonpsychotic).

Neuroendocrine changes in depression

Biological research in depression has concentrated on 'endogenous' depressions and over the past 30 years has been guided by the amine theory. Neuroendocrine abnormalities in depression have been reported for over 20 years and include changes in the hypothalamic-pituitary-adrenal and thyroid axes, in growth hormone and prolactin secretion. As neurotransmitters regulate neuroendocrine secretion, inter-relationships between neurochemical and neuroendocrine abnormalities may provide a window for understanding the pathophysiology of depression. The availability of these biological markers for depression opens new possibilities for research in psychiatric diagnosis and for management.

Social skills training and endogenous depression

The clinical response to social skills training was studied in four women with definite endogenous depression (melancholia) to ascertain if a behavioral intervention could be effective with more severe and pervasive affective syndromes. Three of four patients responded to social skills training, although both patients available for longitudinal follow-up relapsed within 24 months post-treatment. Implications for research and practice are discussed.

Neurophysiological "markers"--EEG sleep measures

Although a number of neurophysiological "markers" have been suggested as potential correlates of depression, the most promising set has been based on the electroencephalographic (EEG) measurement of sleep in affective disorders. Our knowledge, based on episodic biological correlates of depression, has attained considerable consensus in demonstrating specific findings for EEG sleep and depression. While there are some controversial issues remaining, the available evidence suggests that EEG sleep correlates can certainly be used as a state measure in affective disorders. A second phase of inquiry is now concerned with two issues--whether there are any specific markers during remitted phases of depression, and how the data base can help us understand some of the key theoretical biological issues in affective states.

EEG sleep in outpatients with generalized anxiety: a preliminary comparison with depressed outpatients

To develop further perspective on the psychophysiology of generalized anxiety disorder and primary depression, all-night electroencephalographic (EEG) sleep measures in outpatients with diagnoses of generalized anxiety disorder and primary (nondelusional) depression were compared. Both groups had difficulty initiating and maintaining sleep, and diminished amounts of slow-wave sleep. Compared to patients with generalized anxiety disorder, depressives had a shorter rapid eye movement (REM) latency, greater REM sleep percent and eye movement activity, and a different temporal distribution of REM sleep. Anxious patients showed few changes from first to second night, whereas depressives showed increases in several REM sleep indexes. The combination of REM sleep latency and REM percent correctly classified 86.7% of patients. These data may provide a more direct measure of central nervous system arousal and sleep/wake function than previous studies in the psychophysiology of anxiety. They also lend support to the clinical distinction between generalized anxiety disorder and primary depression and to the classification of anxiety states as disorders of initiating and maintaining sleep.

Daytime sleep patterns of primary depressives: a morning nap study

The electroencephalographic sleep patterns of 10 primary depressives were recorded during baseline nights and two morning nap sessions using a fixed time schedule. Averaged sleep measures for baseline nights replicated previous findings of altered rapid eye movement (REM) sleep patterns and sleep continuity. REM sleep during morning naps occurred only in patients with elevated REM indexes on baseline and prenap nights; it failed to appear in morning sleep of patients who exhibited contrasting REM characteristics. An analysis of hourly REM sleep distribution and averaged deviations from group means revealed significant differences between the two groups which could account for the uneven daytime REM propensity.