Electroencephalographic sleep studies in depressed outpatients treated with interpersonal psychotherapy: I. Baseline studies in responders and nonresponders.

Electroencephalographic (EEG) sleep measures have been examined as predictors of therapeutic response in patients with major depression. Although some studies have reported that EEG sleep measures are predictive of a favorable outcome with medications, two recent studies found no differences in the baseline sleep characteristics of responders and nonresponders to psychotherapy. To clarify this issue, we compared baseline EEG sleep in a group of patients with recurrent depression who responded to interpersonal psychotherapy (n = 19) and a comparable group who did not respond (n = 18). Baseline ratings of depression severity did not differ in the groups, but some differences in baseline sleep were noted. Psychotherapy nonresponders had longer sleep latencies, lower sleep efficiency, and increased automated measures of phasic rapid eye movement (REM) activity. In addition, the two groups had different EEG sleep adaptation patterns for REM latency and phasic REM density measures across the two study nights. These preliminary results suggest that baseline EEG sleep patterns, as well as the pattern of laboratory adaptation, may differ for depressed patients who respond to psychotherapy and those who do not.     

Sleep and treatment response in depression: new findings using power spectral analysis

This study examined quantitative measures of sleep electroencephalogram (EEG) and phasic rapid eye movements (REM) as correlates of remission and recovery in depressed patients. To address correlates of remission, pre-treatment EEG sleep studies were examined in 130 women outpatients with major depressive disorder treated with interpersonal psychotherapy (IPT). To address correlates of recovery, baseline and post-treatment EEG sleep studies were examined in 23 women who recovered with IPT alone and 23 women who recovered with IPT+fluoxetine. Outcomes included EEG power spectra during non-rapid eye movement (NREM) sleep and REM sleep and quantitative REMs. IPT non-remitters had increased phasic REM compared with remitters, but no significant differences in EEG power spectra. IPT+fluoxetine recoverers, but not IPT recoverers, showed increases in phasic REM and REM percentage from baseline to recovery. In NREM sleep, the IPT+fluoxetine group showed a decrease in alpha power from baseline to recovery, while the IPT group showed a slight increase. The number of REMs was a more robust correlate of remission and recovery than modeled quantitative EEG spectra during NREM or REM sleep. Quantitative REMs may provide a more direct measure of brainstem function and dysfunction during REM sleep than quantitative sleep EEG measures.     

Rapid eye movement sleep deprivation as a probe in elderly subjects

The effects of a 2-night rapid eye movement (REM) sleep deprivation (RSD) procedure on electroencephalographic sleep and mood were examined in 15 healthy elderly control subjects, 14 elderly patients with endogenous depression, and 15 patients with primary degenerative dementia. Compared with control subjects, both patient groups maintained a higher amount of REM sleep time and REM activity during RSD. Unexpectedly, depressed patients showed little rebound in visually scored or automated REM sleep measures following RSD, and they showed stability of REM activity temporal distribution from baseline to recovery conditions. This contrasted with the rebound in REM sleep activity seen in control subjects, and the more modest increase in demented patients. The RSD was fairly specific, with some impact on delta sleep during the procedure but not during recovery sleep. Mood ratings were unaffected by RSD. These findings demonstrated a greater plasticity of REM sleep regulation in the healthy elderly control subjects and suggested a higher REM "pressure" with a "ceiling effect" in depressed patients. Patients with dementia appeared to have an impaired capacity to respond to the challenge of RSD.     

Sleep, gender, and depression: an analysis of gender effects on the electroencephalographic sleep of 302 depressed outpatients

Gender-related differences in electroencephalographic (EEG) sleep were examined in 151 pairs of men and women with major depression, all outpatients, matched for age and severity of depression. Across five decades (age 21-69), depressed men had less slow-wave sleep than did depressed women. Gender differences were small with respect to visually scored measures of slow-wave sleep time and percent, but moderate for gender differences in automated measures of slow-wave density. The time constant of the polygraph preamplifier significantly affected both visually scored and automatically scored slow-wave sleep. Other measures such as REM sleep latency, first REM period duration, sleep efficiency, and early morning awakening, showed robust age effects, but no main effects for gender or gender-by-age interactions. Gender effects on slow-wave sleep and delta-wave counts in depression parallel gender effects seen in healthy aging. The possibility of occult alcohol use by depressed male outpatients cannot be definitely excluded as a partial explanation of the current findings. However, covarying for past alcohol abuse did not negate the statistical significance of the observed gender effects on slow-wave sleep and delta-wave density. The possibility of gender differences in slow-wave regulatory mechanisms is suggested, but similarity in temporal distribution of delta-wave density between the first and second non-rapid-eye-movement (NREM) periods does not support gender differences in slow-wave sleep regulation.     

Sleep, depression, and suicide

In a retrospective study of the electroencephalographic (EEG) sleep of major depressives with and without a history of suicide attempts, suicide attempters had longer sleep latency, lower sleep efficiency, and fewer late-night delta wave counts than normal controls. Nonattempters, compared to attempters, had less rapid eye movement (REM) time and activity in period 2, but more delta wave counts in non-REM period 4. Although both attempters and nonattempters were like controls in regard to REM period 2, patients with suicide attempts had altered intranight temporal distribution of phasic REM activity, with increased REM activity (by both visual and automated scoring) in REM sleep period 2 (significant group x period interaction). These findings, which may be more traitlike or persistent than state-related, are discussed in the context of current theories on the role of serotonin in the regulation of sleep and in suicidal behavior.     

Sleep and affective disorders. A minireview

The most predictable electroencephalographic sleep changes of major depression are a shortened first NREM sleep period, a prolonged first REM period (with increased density of rapid eye movements), sleep continuity disturbance, and diminished slow wave sleep (with shifting of delta activity from the first to the second NREM sleep period). The more rapid appearance of the first REM sleep period occurs in relation to sleep onset but not apparently in relation to clock time. The changes occurring in the first NREM-REM cycle of the night appear to be relatively specific to major (particularly endogenous) depression. Depressed men appear to have diminished nocturnal penile tumescence compared with healthy controls, but depressed patients generally do not have a higher incidence of sleep apnea or nocturnal myoclonus. The sleep physiologic changes of depression appear to persist into clinical remission, suggesting that they are trait-like. Published studies appear to support the conclusion that there is a close link between the regulation of sleep and the regulation of mood in affective illness.     

Comparison of automated REM and slow-wave sleep analysis in young and middle-aged depressed subjects

A comparison of electroencephalographic sleep measures between young and middle-aged groups of depressed inpatients was conducted with specific interest in the application of automated measures of REM and delta wave sleep. Aside from the expected differences in sleep continuity, increased Stage 1 percent, decreased Stage 2 percent, and decreased REM latency in the middle-aged depressives as compared to the younger depressives, distinct findings from automated analyses were noted in the distribution of REM and delta sleep throughout the night. Although the younger depressed patients showed increased numbers of delta waves, the middle-aged depressives showed greater average REM count. Such changes were more pronounced in the first third of the night. Finally, in the middle-aged depressives, little statistical relationship between manual measures of slow-wave sleep and automated measures of delta sleep was found.     

Electroencephalographic sleep in young, never-medicated schizophrenics. A comparison with delusional and nondelusional depressives and with healthy controls

Electroencephalographic (EEG) sleep characteristics of young, never-medicated, nonschizoaffective schizophrenics were compared with the EEG sleep of patients with major depressive disorders (delusional and nondelusional) and with that of healthy controls. Schizophrenics had decreased sleep continuity comparable to delusional depressives. Slow-wave sleep percent was similar to that seen in healthy controls, as was the intranight temporal distribution of EEG delta activity. However, schizophrenics showed diminished delta counts per minute of non-rapid eye movement (NREM) sleep and a decreased total delta wave count. In contrast, depressives showed diminished slow-wave sleep percent compared with controls, greatly decreased delta activity (more so than did the schizophrenics), and an altered temporal distribution of delta activity, as evidenced by a shift of delta activity from the first to the second NREM period. Minutes of slow-wave sleep in the schizophrenics was inversely correlated with the severity of negative symptoms independent of the effects of age and the presence of depression. The schizophrenics showed normal REM latency and first REM period duration, in contrast to the depressives. These findings, reviewed in the historical context of sleep physiologic studies of schizophrenia over the past 30 years, suggest that young, never-medicated schizophrenics do not show the characteristic constellation of abnormalities in the first NREM-REM cycle seen in patients with major depression. However, decreased slow-wave sleep should be investigated as a possible marker for negative symptoms in schizophrenia.     

Sleep electroencephalography in depression and mental disorders with depressive comorbidity

Traditional scoring of sleep EEG in depressed patients shows abnormalities in sleep maintenance, sleep architecture, REM sleep, the distribution of slow wave and REM sleep during the night. Computerized analysis that comprises the period-amplitude analysis procedure and spectral analysis discloses changes in delta activity and distribution of delta activity. However, these methods of analysing EEG sleep are not able to distinguish the various concepts of depression: endogenous and non-endogenous depression, unipolar and bipolar depression, psychotic and non-psychotic depression. Polysomnographical data in patients with recurrent depression show alteration during remission suggesting trait-like abnormalities of sleep in depression illness. Shortened REM latency is not specific in depression. This sleep parameter is defined in many different ways explaining the heterogeneousness of study results and the failure of constituting a biological marker. Many sleep parameters are affected by several factors such as age, gender and severity. Several physiopathological hypotheses have been proposed to explain EEG sleep alterations. They refer either to circadian rhythms such as the two process model of Borbély, the phase advance hypothesis and the circadian amplitude hypothesis, or to neurotransmitter abnormalities such as the cholinergic hypothesis. None of them takes sufficient account of all the sleep abnormalities. Sleep abnormalities have also been described in other psychiatric disorders such as mania, panic and obsessional-compulsive disorders, generalized anxiety, phobias, post-traumatic stress disorder, eating disorders, borderline personality, schizophrenia and dementia. None of them have a particular sleep EEG profile which allows to differentiate between them. A concomitant episode of major depression cannot be uncovered by sleep recordings.     

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.     

Paradoxes of the first-night effect: a quantitative analysis of antero-posterior EEG topography.

OBJECTIVE: The first-night effect (FNE) is a common issue in sleep research. Being considered fragmented and poorly efficient, the adaptation night is discarded for data analysis. The present study aims to provide a quantitative and topographical EEG analysis of this phenomenon. METHODS: Eight healthy subjects slept for two consecutive nights (adaptation (AD) and baseline (BSL)), and their polysomnography was visually scored and then submitted to spectral power analysis. RESULTS: The results showed a decreased quality and quantity of first-night sleep as indicated by more stage 1 and intrasleep wake, paralleled by a reduced sleep efficiency and a longer sleep onset latency. On the other hand, EEG quantitative data showed a more complex and apparently paradoxical picture. An increase in delta power was observed, particularly over the central areas during the first night, paralleled by an increased power in beta bin frequencies solely at posterior scalp locations. CONCLUSIONS: These results have been interpreted as caused by, respectively, a reduced total sleep time during the adaptation night and a cortical hyperactivity, typical of psychophysiological insomnia. The present results confirm the need to exclude the laboratory sleep adaptation night from data analysis since it is not a reliable index of sleep on subsequent nights as regards both visual scoring and quantitative EEG analysis. Finally, regional differences between REM and NREM sleep have been confirmed. Significance: This is the first attempt to evaluate the FNE with a quantitative approach to the antero-posterior EEG topography, providing both a Hz-by-Hz and a classical EEG band-based analysis.     

Application of automated REM and slow wave sleep analysis: I. Normal and depressed subjects

Computerized analysis of rapid eye movement (REM) and delta electroencephalographic (EEG) sleep patterns in normal and depressed subjects offers opportunities to examine sleep more precisely than previously possible. In the present study, automated REM analyses demonstrated good reliability with traditional manual procedures in both normal and depressed subjects. However, automated delta analyses correlated well with traditional scoring in normal subjects, but not in depressed patients. These findings suggest the use of automated delta techniques similar to those employed in this report or spectral analytic techniques in the following types of studies: specificity of delta sleep in various psychiatric syndromes, changes in delta sleep produced by the administration of psychotropic agents, relationships between delta sleep and sleep-related neuroendocrine patterns, and, finally, relationships between delta sleep patterns and other biological rhythms such as activity and temperature.     

Band-specific electroencephalogram and brain cooling abnormalities during NREM sleep in patients with winter depression.

BACKGROUND: We previously reported that delta wave activity and facial skin temperatures, an index of brain cooling activity, were both abnormal during sleep in patients with winter depression (SAD). Because other electroencephalographic (EEG) frequencies may also convey relevant thermal, homeostatic, and circadian information, we sought to spectrally analyze delta, theta, alpha, and sigma frequencies during sleep from 23 patients with SAD and 23 healthy control subjects. METHODS: We computed means for delta, theta, alpha, and sigma power during both NREM and REM sleep. We also generated 22 cross-correlation functions for each group by crossing facial and rectal temperature with each other, as well as with delta, theta, alpha, and sigma frequencies. RESULTS: We found that delta, theta, and alpha frequency activities were all increased during NREM, but not REM sleep, in patients with SAD. In addition, there were significant and abnormal cross-correlations between facial temperatures and delta and theta frequencies during NREM sleep in patients with SAD. CONCLUSIONS: Patients with winter depression exhibit correlated abnormalities of sleep homeostasis and brain cooling during NREM sleep. Their EEG profiles during NREM sleep resemble the EEG profiles of subjects who have been sleep deprived. Further studies of NREM sleep homeostasis in patients with SAD seem warranted.     

Application of automated REM and slow wave sleep analysis: II. Testing the assumptions of the two-process model of sleep regulation in normal and depressed subjects

Abnormalities in a two-process model of sleep regulation (a sleep-dependent process, termed Process S, and a sleep-independent circadian process, termed Process C) have been proposed to account for sleep abnormalities in depressive states. The major tenets of the two-process model of sleep regulation as applied to depression are: the level of process S, as reflected by the electroencephalographic (EEG) slow-wave activity, corresponds to the sleep-dependent facet of sleep propensity; the pathognomonic changes of sleep in depressives are a consequence of a deficiency in the build-up of process S. The application of automated rapid eye movement (REM) and delta wave analyses in normal subjects and younger depressed patients supports the model to some extent: The time spent asleep is positively correlated with total delta waves (normals and depressives) and average delta waves (depressives); delta sleep is lower in depressives than in normals; the average delta wave count is significantly reduced in younger depressives over the total night and in non-REM period 1. The model also postulates that measures of phasic REM activity are inversely related to process S, suggesting that process S can be regarded as exerting an inhibitory influence on phasic REM activity.     

REM sleep in depression is influenced by ethnicity

The influence of ethnicity on the manifestation of EEG sleep changes in depression was studied in 95 patients (21 African-Americans [AA], 17 Asians [AS], 37 Caucasians [C] and 20 Hispanics [H]) with unipolar major depression. Subjects were studied twice for 2 consecutive nights. On the second night of each 2-night session, placebo or scopolamine (1.5 microg/kg, IM, at 23.00 h) was administered. On the baseline (placebo) night, sleep architecture, sleep continuity and rapid eye movement (REM) sleep variables were generally comparable among the groups. However, REM sleep was less in AA and AS subjects than in C and H subjects. Furthermore, the distribution of REM sleep over the course of the night in AA and AS subjects differed significantly from that in the C and H groups. Although scopolamine significantly affected sleep continuity and REM sleep measures, no significant differential effects of scopolamine were observed. Because many antidepressants suppress REM sleep, the differences in baseline REM sleep observed might be related to the greater sensitivity of some ethnic-minority depressed patients to pharmacotherapy.     

Sleep EEG studies during early and late partial sleep deprivation in premenstrual dysphoric disorder and normal control subjects

In this study of 23 patients with premenstrual dysphoric disorder (PMDD) and 18 normal comparison (NC) subjects, we examined sleep EEG measures during baseline midfollicular (MF) and late luteal (LL) menstrual cycle phases and after early sleep deprivation (ESD), in which subjects slept from 03.00 to 07.00 h, and late sleep deprivation (LSD), in which subjects slept from 21.00 to 01.00 h. Each sleep deprivation night was followed by a night of recovery sleep (ESD-R, LSD-R) (sleep 22.30-06.30 h) and was administered in the late luteal phase of separate menstrual cycles. During baseline studies, sleep EEG measures differed significantly by menstrual cycle phase, but not group. Both PMDD and NC groups showed longer REM latencies and less REM sleep (minutes and percent) during the luteal compared with the follicular menstrual cycle phase. PMDD subjects, however, did not show sleep architecture changes similar to those of patients with major depressive disorders. Sleep quality was better during recovery nights of sleep in PMDD compared with NC subjects. REM sleep measures changed in association with clinical improvement in responders to sleep deprivation. Both early and late sleep deprivation may help to correct underlying circadian rhythm disturbances during sleep in PMDD, although differential sleep changes during ESD vs. LSD did not correlate with clinical response. Further sleep studies addressing additional circadian variables may serve to elucidate mechanisms mediating the therapeutic effects of sleep deprivation in PMDD.     

Sleep as a biomarker for depression

Abstract

Sleep is a complex biological process that involves cyclic changes of brain activity. The smooth transition between wakefulness and sleep and cyclic succession of sleep stages depend on the function of numerous neurotransmitters that reciprocally influence each other. For this reason sleep is a very sensitive biomarker of brain functioning. This article provides an overview of sleep changes in depression, mechanisms involved in sleep regulation and pathophysiology underlying depression, studies on sleep as a biomarker for depression, effects of antidepressants on sleep EEG, and studies in depression with the use of quantitative sleep EEG analysis. Research on sleep in depression has provided several valuable biomarkers that are related to increased risk for depression, show worsening during depressive episode, and are related to treatment outcome and relapse risk during remission phase. Among many sleep parameters, increased REM density and diminished delta sleep ratio deserve special interest. Sleep studies are also an important research tool for antidepressant drug development. However, due to sensitivity of sleep parameters to pharmacological interventions, the patients have to be investigated before the start of pharmacological treatment or after washout from the antidepressant drug, to obtain reliable data on disease-related biological processes from polysomnography.     

Effect of neuroleptic treatment on polysomnographic measures in schizophrenia.

To study the effects of neuroleptic therapy on sleep EEG variables in schizophrenia, as well as the clinical correlates of these variables, we performed polysomnographic (PSG) studies on 14 schizophrenic inpatients before and during neuroleptic therapy. Sleep continuity measures improved after 3 weeks of neuroleptic therapy, showing decreased sleep latency and improved sleep efficiency. REM latency increased with treatment, although half the patients continued to exhibit REM latencies less than 60 min. Other sleep stages and measures of REM sleep (density, activity, number of periods) did not appear to change with neuroleptic treatment. At baseline, REM latency had strong negative correlations with BPRS and SANS scores, but with 3 weeks of such treatment, this association disappeared. Further work is needed to distinguish direct medication effects from the effects of the changing clinical state on PSG measures.     

Clomipramine and EEG sleep in depression

Recent studies with clomipramine (CMI) have demonstrated that a pulse-loading approach is associated with a rapid improvement in symptomatology in the absence of continuous treatment. In the present study, sleep changes were evaluated to ascertain the rapidity of clomipramine's effect on electroencephalographic sleep, especially rapid eye movement (REM) and delta wave sleep measures. Clomipramine produced rapid changes in sleep with reduced sleep continuity and almost complete suppression of REM sleep as well as a redistribution of slow wave sleep. Delta waves during sleep were also found to be shifted to the earlier part of the night and increased in intensity. Spectral analysis revealed an increase in power in the delta frequency range that was correlated with clinical responsiveness. These studies point toward a role for clomipramine in the rapid treatment of depression and confirm that sleep physiology may be a good predictor of antidepressant action.     

The application of EEG sleep for the differential diagnosis of affective disorders.

On the basis of two EEG sleep criteria, REM latency and REM activity, the authors achieved 81% accuracy in distinguishing between 47 patients with primary depression and 48 patients with secondary depression using discriminant analysis. Sleep efficiency, the percentage of delta sleep, and the percentage of REM sleep discriminated between psychotic and nonpsychotic subgroups in the group with primary depression with 75% accuracy. REM activity and intermittent nocturnal awakening accurately discriminated two subtypes of patients with secondary depression at a level of 81%. These results suggest that EEG sleep measurements can yield significant data to aid in differential diagnosis in psychiatry.