Naps after total sleep deprivation in depressed patients: are they depressiogenic?

Effects of dim-evening lighting optimised for geographical orientation versus standard lighting on mental health: protocol paper for a quasiexperimental study in a psychiatric hospital

INTRODUCTION

Research has provided novel insights into how light stimulates circadian rhythms through specialised retinal ganglion cells to the suprachiasmatic nucleus. In addition, there has been a revolution in light-emitting diode (LED) technology, leading to tunable LED light sources and lighting systems, enabling 24-hour dynamic light scenarios with bright blue-enriched short wavelength light during the day and dim evening light, stimulating the circadian system. These dynamic LED lighting systems are now being implemented at hospitals without adequate understanding of how it may affect the health and well-being of patients and staff.

METHODS AND ANALYSIS

An optimised dynamic LED lighting scenario is investigated at a newly built psychiatric hospital in Copenhagen. In the 12 months baseline period, a standard lighting scenario with dynamic colour temperature and fixed light intensity is investigated. In the following 12-month intervention period, a new DEL scenario is investigated, having dynamic colour temperature as well as dynamic light intensity with a higher daytime and lower evening-time melanopic daylight equivalent illuminance. This setting is furthermore adjusted for geographical orientation to compensate for differences in sunlight access in wintertime. The study uses a quasiexperimental design comparing patients admitted in the two study periods. Prior to each of the study periods, daylight and the contribution from the LED-lighting scenarios was measured. Patient sociodemographic and mental health data will be retrieved retrospectively from electronic medical records and by questionnaires administered in the two periods, evaluating lighting, noise, sleep quality and quality of life. Primary outcome is the proportion of patients receiving pro re nata medications. Secondary outcomes are the length of stay, sleep onset latency, sleep quality and quality of life.

ETHICS AND DISSEMINATION

No ethical issues are expected. The results will be disseminated through peer-reviewed international journal, lectures, posters and interviews.

TRIAL REGISTRATION NUMBER

NCT05868291.

Treatment-resistant depression: Neurobiological correlates and the effect of sleep deprivation with sleep phase advance for the augmentation of pharmacotherapy

OBJECTIVES

To assess the neurobiology of treatment-resistant depression (TRD), and factors connected with improvement after total sleep deprivation (TSD) with sleep phase advance (SPA), for the augmentation of pharmacotherapy.

METHODS

The study comprised 43 patients with TRD, (15 male, 28 female), aged 48 ± 13 years, with the illness duration 12 ± 9 years, and the depressive episode 8 ± 7 months. TRD was defined as a lack of significant improvement despite at least two antidepressant treatments and the augmentation with mood-stabilisers. Clinical improvement (response) was a reduction of ≥50% of points in the Hamilton Depression Rating Scale (HDRS), and the remission criterion was ≤7 points in HDRS, lasting until the 14th day after TSD + SPA.

RESULTS

TRD severity was associated with greater activity of the hypothalamic-pituitary-adrenal axis, the pro-inflammatory status of the immune system and lower reactivity of the hypothalamic-pituitary-thyroid axis. The response was achieved by 18 of 42 subjects, and connected with the later onset and shorter duration of the disease. In responders, there was a decrease in cortisol and interferon-gamma. In all subjects, a decrease in thyroid hormones was observed.

CONCLUSIONS

TRD can improve after augmentation of pharmacotherapy by TSD + SPA and some biological changes may be compatible with a decrease in allostatic load.

Clarifying the role of sleep in depression: A narrative review

It has been established that 4.4 to 20% of the general population suffers from a major depressive disorder (MDD), which is frequently associated with a dysregulation of normal sleep-wake mechanisms. Disturbances of circadian rhythms are a cardinal feature of psychiatric dysfunctions, including MDD, which tends to indicate that biological clocks may play a role in their pathophysiology. Thus, episodes of depression and mania or hypomania can arise as a consequence of the disruption of zeitgebers (time cues). In addition, the habit of sleeping at a time that is out of phase with the body's other biological rhythms is a common finding in depressed patients. In this review, we have covered a vast area, emerging from human and animal studies, which supports the link between sleep and depression. In doing so, this paper covers a broad range of distinct mechanisms that may underlie the link between sleep and depression. This review further highlights the mechanisms that may underlie such link (e.g. circadian rhythm alterations, melatonin, and neuroinflammatory dysregulation), as well as evidence for a link between sleep and depression (e.g. objective findings of sleep during depressive episodes, effects of pharmacotherapy, chronotherapy, comorbidity of obstructive sleep apnea and depression), are presented.

Sleep, insomnia, and depression

Since ancient times it is known that melancholia and sleep disturbances co-occur. The introduction of polysomnography into psychiatric research confirmed a disturbance of sleep continuity in patients with depression, revealing not only a decrease in Slow Wave Sleep, but also a disinhibition of REM (rapid eye movement) sleep, demonstrated as a shortening of REM latency, an increase of REM density, as well as total REM sleep time. Initial hopes that these abnormalities of REM sleep may serve as differential-diagnostic markers for subtypes of depression were not fulfilled. Almost all antidepressant agents suppress REM sleep and a time-and-dose-response relationship between total REM sleep suppression and therapeutic response to treatment seemed apparent. The so-called Cholinergic REM Induction Test revealed that REM sleep abnormalities can be mimicked by administration of cholinomimetic agents. Another important research avenue is the study of chrono-medical timing of sleep deprivation and light exposure for their positive effects on mood in depression. Present day research takes the view on insomnia, i.e., prolonged sleep latency, problems to maintain sleep, and early morning awakening, as a transdiagnostic symptom for many mental disorders, being most closely related to depression. Studying insomnia from different angles as a transdiagnostic phenotype has opened many new perspectives for research into mechanisms but also for clinical practice. Thus, the question is: can the early and adequate treatment of insomnia prevent depression? This article will link current understanding about sleep regulatory mechanisms with knowledge about changes in physiology due to depression. The review aims to draw the attention to current and future strategies in research and clinical practice to the benefits of sleep and depression therapeutics.

Association of Locomotor Activity During Sleep Deprivation Treatment With Response

Disrupted circadian rhythms and sleep patterns are frequently observed features of psychiatric disorders, and especially mood disorders. Sleep deprivation treatment (SD) exerts rapid but transient antidepressant effects in depressed patients and has gained recognition as a model to study quick-acting antidepressant effects. It is of interest how locomotor activity patterns during SD might be associated with and potentially predict treatment response. The present study is an analysis of locomotor activity data, previously collected over a 24 h period, to examine the night of SD (Trautmann et al. 2018) as mood disorder patients suffering from a depressive episode (n = 78; after exclusions n = 59) underwent SD. In this exploratory analysis, the associations between response to SD, locomotor activity, and subjective mood during the 24 h period of SD were explored. Higher levels of activity overall were observed in non-responders (n = 18); in particular, non-responders moved more during the evening of SD until midnight and remained high thereafter. In contrast, activity in responders (n = 41) decreased during the evening and increased in the morning. Subjective mood was not found to be associated with locomotor activity. The window of data available in this analysis being limited, additional data from before and after the intervention are required to fully characterize the results observed. The present results hint at the possible utility of locomotor activity as a predictor and early indicator of treatment response, and suggest that the relationship between SD and locomotor activity patterns should be further investigated.

Wake and light therapy for moderate-to-severe depression - a randomized controlled trial

OBJECTIVE

To examine the efficacy of using wake and light therapy as a supplement to standard treatment of hospitalized patients with depression.

METHOD

In this randomized, controlled study, 64 patients with moderate-to-severe depression were allocated to standard treatment or to the intervention, which additionally consisted of three wake therapy sessions in one week, 30-min daily light treatment and sleep time stabilization over the entire nine-week study period.

RESULTS

Patients in the wake therapy group had a significant decrease in depressive symptoms in week one as measured by HAM-D₁₇ , 17.39 (CI 15.6-19.2) vs. 20.19 (CI 18.3-22.09) (P = 0.04), whereas no statistically significant differences were found between the groups in weeks two to nine. At week nine, the wake therapy group had a significantly larger increase in general self-efficacy (P = 0.001), and waking up during nights was a significantly less frequent problem (1.9 times vs. 3.2) (P = 0.0008). In most weeks, significantly fewer patients in the wake therapy group slept during the daytime, and if they slept, their naps were shorter (week three: 66 min vs. 117 min P = 0.02).

CONCLUSION

The antidepressant effect initially achieved could not be maintained during the nine-week study period. However, sleep and general self-efficacy improved.

Neural Plasticity Is Involved in Physiological Sleep, Depressive Sleep Disturbances, and Antidepressant Treatments

Depression, which is characterized by a pervasive and persistent low mood and anhedonia, greatly impacts patients, their families, and society. The associated and recurring sleep disturbances further reduce patient's quality of life. However, therapeutic sleep deprivation has been regarded as a rapid and robust antidepressant treatment for several decades, which suggests a complicated role of sleep in development of depression. Changes in neural plasticity are observed during physiological sleep, therapeutic sleep deprivation, and depression. This correlation might help us to understand better the mechanism underlying development of depression and the role of sleep. In this review, we first introduce the structure of sleep and the facilitated neural plasticity caused by physiological sleep. Then, we introduce sleep disturbances and changes in plasticity in patients with depression. Finally, the effects and mechanisms of antidepressants and therapeutic sleep deprivation on neural plasticity are discussed.

Mood, the Circadian System, and Melanopsin Retinal Ganglion Cells

The discovery of a third type of photoreceptors in the mammalian retina, intrinsically photosensitive retinal ganglion cells (ipRGCs), has had a revolutionary impact on chronobiology. We can now properly account for numerous non-vision-related functions of light, including its effect on the circadian system. Here, we give an overview of ipRGCs and their function as it relates specifically to mood and biological rhythms. Although circadian disruptions have been traditionally hypothesized to be the mediators of light's effects on mood, here we present an alternative model that dispenses with assumptions of causality between the two phenomena and explains mood regulation by light via another ipRGC-dependent mechanism.

Chronobiological Therapy for Mood Disorders

Chronobiological therapies for mood disorders include manipulations of the sleep-wake cycle such as sleep deprivation and sleep phase advance and the controlled exposure to light and darkness. Their antidepressant efficacy can overcome drug resistance and targets the core depressive symptoms including suicide, thus making them treatment options to be tried either alone or as adjunctive treatments combined with common psychopharmacological interventions. The specific pattern of mood change observed with chronobiological therapies is characterized by rapid and sustained effects, when used among themselves or combined with drugs. Effects sizes are the same reported for the most effective psychiatric treatments, but side effects are usually marginal or absent. New treatment protocols are developed to adapt them in different clinical settings. This review deals with the general principles of clinical chronobiology and the latest findings in this rapidly developing field.

Synaptic plasticity model of therapeutic sleep deprivation in major depression

Therapeutic sleep deprivation (SD) is a rapid acting treatment for major depressive disorder (MDD). Within hours, SD leads to a dramatic decrease in depressive symptoms in 50-60% of patients with MDD. Scientifically, therapeutic SD presents a unique paradigm to study the neurobiology of MDD. Yet, up to now, the neurobiological basis of the antidepressant effect, which is most likely different from today's first-line treatments, is not sufficiently understood. This article puts the idea forward that sleep/wake-dependent shifts in synaptic plasticity, i.e., the neural basis of adaptive network function and behavior, represent a critical mechanism of therapeutic SD in MDD. Particularly, this article centers on two major hypotheses of MDD and sleep, the synaptic plasticity hypothesis of MDD and the synaptic homeostasis hypothesis of sleep-wake regulation, and on how they can be integrated into a novel synaptic plasticity model of therapeutic SD in MDD. As a major component, the model proposes that therapeutic SD, by homeostatically enhancing cortical synaptic strength, shifts the initially deficient inducibility of associative synaptic long-term potentiation (LTP) in patients with MDD in a more favorable window of associative plasticity. Research on the molecular effects of SD in animals and humans, including observations in the neurotrophic, adenosinergic, monoaminergic, and glutamatergic system, provides some support for the hypothesis of associative synaptic plasticity facilitation after therapeutic SD in MDD. The model proposes a novel framework for a mechanism of action of therapeutic SD that can be further tested in humans based on non-invasive indices and in animals based on direct studies of synaptic plasticity. Further determining the mechanisms of action of SD might contribute to the development of novel fast acting treatments for MDD, one of the major health problems worldwide.

Napping reverses the salivary interleukin-6 and urinary norepinephrine changes induced by sleep restriction

CONTEXT

Neuroendocrine and immune stresses imposed by chronic sleep restriction are known to be involved in the harmful cardiovascular effects associated with poor sleep.

OBJECTIVES

Despite a well-known beneficial effect of napping on alertness, its effects on neuroendocrine stress and immune responses after sleep restriction are largely unknown.

DESIGN

This study was a strictly controlled (sleep-wake status, light environment, caloric intake), crossover, randomized design in continuously polysomnography-monitored subjects.

SETTING

The study was conducted in a laboratory-based study.

PARTICIPANTS

The subjects were 11 healthy young men.

INTERVENTION

We investigated the effects on neuroendocrine and immune biomarkers of a night of sleep restricted to 2 h followed by a day without naps or with 30 minute morning and afternoon naps, both conditions followed by an ad libitum recovery night starting at 20:00.

MAIN OUTCOME MEASURES

Salivary interleukin-6 and urinary catecholamines were assessed throughout the daytime study periods.

RESULTS

The increase in norepinephrine values seen at the end of the afternoon after the sleep-restricted night was not present when the subjects had the opportunity to take naps. Interleukin-6 changes observed after sleep deprivation were also normalized after napping. During the recovery day in the no-nap condition, there were increased levels of afternoon epinephrine and dopamine, which was not the case in the nap condition. A recovery night after napping was associated with a reduced amount of slow-wave sleep compared to after the no-nap condition.

CONCLUSIONS

Our data suggest that napping has stress-releasing and immune effects. Napping could be easily applied in real settings as a countermeasure to the detrimental health consequences of sleep debt.

The day-to-day acute effect of wake therapy in patients with major depression using the HAM-D6 as primary outcome measure: results from a randomised controlled trial

BACKGROUND

This paper reports day-to-day data for from a one-week intervention phase, part of a 9-weeks randomised parallel study with patient having major depression (data from weekly visits have been reported). Wake therapy (sleep deprivation) has an established antidepressant effect with onset of action within hours. Deterioration on the following night's sleep is, however, common, and we used daily light therapy and sleep time stabilisation as a preventive measure. In particular, we evaluated the day-to-day acute effect of and tolerance to sleep deprivation and examined predictors of response.

METHODS

Patients were assessed at psychiatric inpatient wards. In the wake group (n = 36), patients did three wake therapies in combination with light therapy each morning together with sleep time stabilisation. In the exercise group (n = 38), patients did daily exercise. Hamilton subscale scores were primary outcome (not blinded), secondary outcome was self-assessment data from the Preskorn scale and sleep.

RESULTS

Patients in the wake therapy group had an immediate, large, stable, and statistically significant better antidepressant effect than patients in the exercise group with response rates at day5 of 75.0%/25.1% and remission rates of 58.6%/6.0%, respectively. The response and remission rates were diminished at day8 with response rates of 41.9%/10.1% and remission rates of 19.4%/4.7%, respectively. Patients and ward personnel found the method applicable with few side effects. Positive diurnal variation (mood better in the evening) predicted a larger response to wake therapy. In the wake group napping on days after intervention predicted greater deterioration on day8.

CONCLUSIONS

The intervention induced an acute antidepressant response without relapse between wake nights but with a diminishing effect after intervention. Development is still needed to secure maintenance of response. Avoiding napping in the days after wake therapy is important.

TRIAL REGISTRATION

Clinical trials.gov NCT00149110.

Mechanisms of rapid antidepressant effects of sleep deprivation therapy: clock genes and circadian rhythms

A significant subset of both major depressive disorder and bipolar disorder patients rapidly (within 24 hours) and robustly improves with the chronotherapeutic intervention of sleep deprivation therapy (SDT). Major mood disorder patients are reported to have abnormal circadian rhythms including temperature, hormonal secretion, mood, and particularly sleep. These rhythms are modulated by the clock gene machinery and its products. It is hypothesized that SDT resets abnormal clock gene machinery, that relapse of depressive symptoms during recovery night sleep reactivates abnormal clock gene machinery, and that supplemental chronotherapies and medications can block relapse and help stabilize circadian-related improvement. The central circadian clock genes, BMAL1/CLOCK (NPAS2), bind to Enhancer Boxes to initiate the transcription of circadian genes, including the period genes (per1, per2, per3). It is suggested that a defect in BMAL1/CLOCK (NPAS2) or in the Enhancer Box binding contributes to altered circadian function associated, in part, with the period genes. The fact that chronotherapies, including SDT and sleep phase advance, are dramatically effective suggests that altered clock gene machinery may represent a core pathophysiological defect in a subset of mood disorder patients.

The depressed patient in a biological world: on philosophical and diagnostic strategies

RATIONALE, AIMS AND OBJECTIVE

We questioned: what kind of relationships between mental and neurobiological levels of complexity is or could become useful in the psychiatric practice? The concept of mind and associated mood states defended here is that they are physically emergent, subjective, qualitative, unified features of the brain. We compared our neurobiological assessment also to psychoanalytical practice (first person's perspective).

ARGUMENT

Applied to recent work on major depressive disorder (MDD), our ideas are among other supported by clinical and experimental studies on sleep deprivation, deep brain stimulation and epidemiological assessments of time-to-recovery.

CLINICAL IMPLICATIONS

We suggest that depression is a transient state of the brain, that is mutually exclusive to the state of pleasure (in the Freudian context), rather than a disorder or disease with a characteristic time course (like many reversible somatic diseases). MDD can best be described with stochastic transition models, which is discussed in the context of a presumed brain serotonin dysfunction in depression. Our ideas invite a reconsideration of some concepts underlying current diagnostic and therapeutic approaches in the clinical practice.

REM sleep dysregulation in depression: state of the art

Disturbances of sleep are typical for most depressed patients and belong to the core symptoms of the disorder. Since the 1960s polysomnographic sleep research has demonstrated that besides disturbances of sleep continuity, depression is associated with altered sleep architecture, i.e., a decrease in slow wave sleep (SWS) production and disturbed rapid eye movement (REM) sleep regulation. Shortened REM latency (i.e., the interval between sleep onset and the occurrence of the first REM period), increased REM sleep duration and increased REM density (i.e., the frequency of rapid eye movements per REM period) have been considered as biological markers of depression which might predict relapse and recurrence. High risk studies including healthy relatives of patients with depression demonstrate that REM sleep alterations may precede the clinical expression of depression and may thus be useful in identifying subjects at high risk for the illness. Several models have been developed to explain REM sleep abnormalities in depression, like the cholinergic-aminergic imbalance model or chronobiologically inspired theories, which are reviewed in this overview. Moreover, REM sleep alterations have been recently considered not only as biological "scars" but as true endophenotypes of depression. This review discusses the genetic, neurochemical and neurobiological factors that have been implicated to play a role in the complex relationships between REM sleep and depression. We hypothesize on the one hand that REM sleep dysregulation in depression may be linked to a genetic predisposition/vulnerability to develop the illness; on the other hand it is conceivable that REM sleep disinhibition in itself is a part of a maladaptive stress reaction with increased allostatic load. We also discuss whether the REM sleep changes in depression may contribute themselves to the development of central symptoms of depression such as cognitive distortions including negative self-esteem and the overnight consolidation of negatively toned emotional memories.

Total sleep deprivation followed by sleep phase advance and bright light therapy in drug-resistant mood disorders

BACKGROUND

Drug-resistant depression is a major therapeutic issue in psychiatry and the development of non-drug therapies that treat drug-resistant depression is required. Sleep deprivation (SD) is a non-drug treatment classified as a form of chronotherapy in addition to bright light therapy (BLT) and sleep phase advance (SPA). Combined chronotherapy is hypothesized to improve drug-resistant depression. In this study, we investigated the benefits of total sleep deprivation (TSD) followed by SPA and BLT in drug-resistant depression alongside ongoing antidepressant medication and observed the added effectiveness of the combined chronotherapy.

METHODS

Thirteen drug-resistant inpatients affected by a major depressive episode were studied. They were treated by TSD followed by SPA (three days) and BLT (five days) with ongoing drug treatment. Effectiveness was rated using the Hamilton Rating Scale for Depression (HAM-D), the Zung Self-Rating Depression Scale (SDS), and the Visual Analogue Scale (VAS) over 3 weeks.

RESULTS

Significant improvements of depressive symptoms were observed in both objective mood ratings (HAM-D) and subjective mood ratings (SDS and VAS). Eight out of 13 patients maintained this responsiveness (50% or greater changes in HAM-D) across the study period. Moreover, no patients dropped out of the combined chronotherapy procedure.

LIMITATIONS

The study did not have a placebo group, and more subjects may be needed.

CONCLUSION

The trial of combined chronotherapy successfully induced rapid improvement in depressive symptoms in drug-resistant patients without early relapse or obvious side effects.

Sleep deprivation in mood disorders

Growing clinical evidence in support of the efficacy and safety of sleep deprivation (SD), and its biological mechanisms of action suggest that this technique can now be included among the first-line antidepressant treatment strategies for mood disorders. SD targets the broadly defined depressive syndrome, and can be administered according to several different treatment schedules: total versus partial, single versus repeated, alone or combined with antidepressant drugs, mood stabilizers, or other chronotherapeutic techniques, such as light therapy and sleep phase advance. The present review focuses on clinical evidence about the place of SD in therapy, its indications, dosage and timing of the therapeutic wake, interactions with other treatments, precautions and contraindications, adverse reactions, mechanism of action, and comparative efficacy, with the aim of providing the clinical psychiatrist with an updated, concise guide to its application.

The possibility of evidence-based psychiatry: depression as a case

Considering psychiatry as a medical discipline, a diagnosis identifying a disorder should lead to an effective therapy. Such presumed causality is the basis of evidence-based psychiatry. We examined the strengths and weaknesses of research onto the causality of relationship between diagnosis and therapy of major depressive disorder and suggest what could be done to strengthen eventual claims on causality. Four obstacles for a rational evidence-based psychiatry were recognised. First, current classification systems are scientifically nonfalsifiable. Second, cerebral processes are—at least to some extent—nondeterministic, i.e. they are random, stochastic and/or chaotic. Third, the vague or lack of relationship between therapeutic regimens and suspected pathogenesis. Fourth, the inadequacy of tools to diagnose and delineate a functional disorder. We suggest a strategy to identify diagnostic prototypes that are characterised by a limited number of parameters (symptoms, markers and other characteristics). A prototypical diagnosis that may either support or reject particular elements of current diagnostic systems. Nevertheless, one faces the possibility that psychiatry will remain a relatively weak evidence-based medical discipline.

Modafinil reduces microsleep during partial sleep deprivation in depressed patients

OBJECTIVE

Sleep deprivation (SD) can induce a prompt decrease in depressive symptoms within 24h. Following the recovery night, however, a relapse into depression occurs in most patients. Recovery sleep, naps and even very short episodes of sleep (microsleep; MS) during SD have been shown to provoke a rapid relapse into depression. This study tested the hypothesis that modafinil reduces MS during SD and stabilizes the treatment response to PSD compared to placebo.

METHODS

A total of 28 patients (13 men, 15 women; age 45.1+/-12.1 years) with a major depressive episode and a cumulative daytime microsleep of five or more minutes were investigated using a double-blind placebo-controlled study design. All patients were treated with a stable mirtazapine monotherapy. A partial SD (PSD) was performed after one week. Additional morning treatment with modafinil vs. placebo started during PSD and was maintained over two weeks. Sleep-EEG and MS episodes were recorded with a portable EEG. Depression severity was assessed using the Hamilton Depression Rating Scale before, during and after PSD and at follow-ups after one and two weeks.

RESULTS

Patients treated with modafinil showed significantly reduced microsleep during PSD (11.63+/-15.99 min) compared to the placebo group (47.77+/-65.31 min). This suppression of MS was not associated with the antidepressive effect of PSD.

CONCLUSIONS

Compared to placebo, modafinil was efficient in reducing daytime microsleep following partial sleep deprivation but did not enhance the antidepressive effects of PSD and did not stabilize antidepressive effects over two weeks.

Effect of flumazenil-augmentation on microsleep and mood in depressed patients during partial sleep deprivation

The antidepressive effect of sleep deprivation (SD) in depressed patients disappears after sleep of the recovery night and after early morning naps. Both can provoke a rapid relapse into depression in SD-responders. In addition, the occurrence of short episodes of sleep (termed microsleep, MS) during partial SD (PSD) is associated with SD-nonresponse, suggesting that MS during the time awake may be related to relapse or PSD-nonresponse. The GABA-benzodiazepine receptor antagonist flumazenil augments vigilance and reduces NonREM-sleep pressure in early morning recovery sleep in volunteers after SD. Therefore, in this study 27 patients with major depression were subjected to a PSD. In a double blind randomized design either flumazenil or placebo was orally applied during PSD in order to examine whether the application of flumazenil reduces sleep propensity and thus, increases antidepressant efficacy of PSD. EEG was registered continuously for 60h by a portable device for the assessment of microsleep episodes at baseline and during PSD. Flumazenil application significantly suppressed frequency and total amount of MS. While the antidepressant efficacy of PSD was not different between flumazenil and placebo during PSD, the subjective mood improved after the recovery night in patients treated with flumazenil. It is concluded that GABAergic mechanisms are involved in the regulation of MS during PSD, which may be related to a mood stabilizing effect after the recovery night. However, the mechanisms underlying the association between the occurrence of MS during PSD and mood variation have to be further clarified.

Sleep and manipulations of the sleep-wake rhythm in depression

OBJECTIVE

Disturbed sleep is typical for most depressed patients and complaints about disordered sleep are the hallmarks of the disorder. Polysomnographic sleep research has demonstrated that besides impaired sleep continuity, sleep in depression is characterized by a reduction of slow wave sleep and a disinhibition of random eye movement (REM) sleep, with a shortening of REM latency, a prolongation of the first REM period and increased REM density.

METHOD

Our own experimental work has focused on the reciprocal interaction hypothesis of non-REM and REM sleep regulation as a model to explain the characteristic features of depressed sleep.

RESULTS

In agreement with the major tenet of this model, administration of cholinomimetics provoked shortened REM latency in healthy subjects and led to an even stronger REM sleep disinhibition in depressed patients. Manipulations of the sleep-wake cycle, such as sleep deprivation or a phase advance of the sleep period, alleviate depressive symptoms.

CONCLUSION

These data indicate a strong bidirectional relationship between sleep, sleep alterations and depression.

Sleep deprivation as a model experimental antidepressant treatment: findings from functional brain imaging

This paper reviews the functional brain imaging studies in depressed patients treated with sleep deprivation. Sleep deprivation is an excellent experimental model of antidepressant treatments which offer new opportunities to understand the basic neural mechanisms. Its antidepressant effects are efficacious and rapid; sleep deprivation is easy to administer, inexpensive, and relatively safe; it can be studied in patients, normal controls, and animals; and it may lead to new treatments and new paradigms for antidepressant therapies. Seven published papers, coming from five different research centers, using either positron emission tomography (PET) with 18fluorodeoxyglucose (FDG) or single photon emission computerized tomography (SPECT) with Technetium-99-bexamethyl propyleneamine oxime (HMPAO) have relatively consistent findings. First, before sleep deprivation, responders have significantly elevated metabolism compared with non-responders, and usually the normal controls, in the orbital medial prefrontal cortex, and especially in the ventral portions of the anterior cingulate cortex. Secondly, after sleep deprivation, these hyperactive areas normalize in the responders. The magnitude of the clinical improvement was significantly correlated with decreased local glucose metabolic rate or cerebral blood flow in three studies. The results are consistent with some but not all functional brain imaging studies of antidepressant medications in depressed patients. Finally, a SPECT study using a radioactively labeled D2 receptor antagonist suggests that the antidepressant benefits of sleep deprivation are correlated with endogenous release of dopamine.

Sleep and depression--results from psychobiological studies: an overview

Disturbances of sleep are typical for most depressed patients and belong to the core symptoms of the disorder. Polysomnographic sleep research has demonstrated that besides disturbances of sleep continuity, in depression sleep is characterized by a reduction of slow wave sleep and a disinhibition of REM sleep, with a shortening of REM latency, a prolongation of the first REM period and increased REM density. These findings have stimulated many sleep studies in depressive patients and patients with other psychiatric disorders. In the meantime, several theoretical models, originating from basic research, have been developed to explain sleep abnormalities of depression, like the two-process-model of sleep and sleep regulation, the GRF/CRF imbalance model and the reciprocal interaction model of non-REM and REM sleep regulation. Interestingly, most of the effective antidepressant agents suppress REM sleep. Furthermore, manipulations of the sleep-wake cycle, like sleep deprivation or a phase advance of the sleep period, alleviate depressive symptoms. These data indicate a strong bi-directional relationship between sleep, sleep alterations and depression.

Delta sleep ratio as a predictor of sleep deprivation response in major depression

The fast but short-lasting improvement of depressive symptoms by sleep deprivation (SD) in about 60% of patients with a major depressive disorder is well established, but the mechanisms of action are still not clear. Recent studies suggest that changes in non rapid eye movement (NREM) sleep, especially in slow wave activity (SWA), could be associated with the therapeutic outcome of SD. In the current study, spectral analysis of NREM sleep EEG directly prior to SD was performed to determine if automatically derived sleep parameters predict SD response. Sixteen pair matched and drug free patients with a major depressive disorder, 8 SD responders and 8 non-responders (response criterion: 50% reduction on the 6-item HAMD score), were included. Average EEG spectral power was calculated for the whole night before SD and for single NREM episodes. While whole-night averages of spectral power did not differ significantly between subgroups, SD responders showed a steady decrease of SWA across successive NREM episodes, whereas in non-responders an increase from the first to the second episode was observed. The different distribution of SWA was significantly expressed in the delta sleep ratio (quotient of SWA in the first to the second NREM episode). In conclusion, a high delta sleep ratio is a positive predictor for SD response. Referred to psycho- and pharmacotherapeutic results it is hypothesized that low and high values of the delta sleep ratio characterize subgroups of depressed patients with different neurobiological alterations, which could be relevant for further scientific and therapeutic approaches.

Patterns of response to repeated total sleep deprivations in depression

BACKGROUND

Patterns of response and nonresponse in repeated sleep deprivation (SD) are of both clinical and scientific interest; as yet, studies have yielded inconsistent results.

METHODS

Eighteen inpatients suffering from a major depression were subjected to a series of six scheduled total sleep deprivations within 3 weeks; 12 of them completed the whole protocol. All were under a constant antidepressant medication with amitriptyline. SD effects were measured using observer and self rating scales.

RESULTS

Each single SD led to a significant improvement. Of the 12 patients who completed the protocol, seven were classified as responders at endpoint (i.e., 1 week after the sixth TSD). The majority of patients exhibited a pattern of responses and nonresponses randomly distributed over time. There was no temporal trend. The initial effect did not predict the average response to the following SDs.

LIMITATIONS

One third of patients dropped out before completing the protocol which limits the scope of the study.

CONCLUSIONS

Response to a single SD is not generalizable on a series of following SDs in an individual. The mechanism of action of SD does probably not involve mechanisms subjected to habituation or sensitization.

Total sleep deprivation combined with lithium and light therapy in the treatment of bipolar depression: replication of main effects and interaction

The clinical usefulness of total sleep deprivation (TSD) in the treatment of bipolar depression is hampered by a high-rate short-term relapse. Previous literature has suggested that both long-term lithium treatment and light therapy could successfully prevent relapse. We randomized 115 bipolar depressed inpatients to receive three cycles of TSD, alone or in combination with morning light exposure, given at an intensity of 150 or 2500 lux. Forty-nine patients were undergoing long-term treatment with lithium salts (at least 6 months), while 66 patients were taking no psychotropic medication. Mood was self-rated by the Visual Analogue Scale three times a day during treatment. The results showed that both light therapy and ongoing lithium treatment significantly enhanced the effects of TSD on the perceived mood, with no additional benefit when the two treatments were combined. Subjective sleepiness during TSD, as rated by the self-administered Stanford Sleepiness Scale, was significantly reduced by light exposure, and was correlated with the outcome. This study confirms the possibility of obtaining a sustained antidepressant response to TSD in bipolar patients.

REM sleep disinhibition at sleep onset: a comparison between narcolepsy and depression

Shortened REM latency and increased REM density are frequently observed in both narcolepsy and depression, suggesting a common mechanism of REM sleep disinhibition in these disorders. We compared night sleep recordings of 24 depressive and 24 narcoleptic patients. The amount of REM sleep and REM density did not differ between the patient groups; however, REM latency distributions differed significantly. Whereas in narcoleptic patients REM episodes started either immediately at sleep onset or following at least 60 min of non-REM sleep, in depressives two thirds of REM latencies were in the range from 1 to 60 min. In narcoleptic patients, short as compared to long REM latencies were associated with longer total sleep time, greater sleep efficiency, reduced amounts of wakefulness, and increased amounts of slow-wave sleep. In depressive subjects the reverse pattern was seen. We conclude that a common mechanism of REM sleep disinhibition in narcolepsy and depression is very unlikely.

Critical analysis of the theories advanced to explain short REM sleep latencies and other sleep anomalies in several psychiatric conditions

One of the most consistent and most studied sleep modifications in several psychiatric conditions is the shortening of the rapid eye movement (REM) sleep latency. While its clinical usefulness is still to be proven and its meaning relatively obscure, the appearance of a short REM latency continues to be a daily fact in sleep laboratories. Many theories compete to explain what is observed, the most important being the circadian rhythm hypotheses, the homeostatic model and the reciprocal interaction model. These three are summarised and their pros and cons are exposed in a systematic manner. Points of conflict, possible convergences and limitations are discussed in the light of recent developments on the general theories of sleep regulation.

Advanced vs. normal sleep timing: effects on depressed mood after response to sleep deprivation in patients with a major depressive disorder

Total sleep deprivation (TSD) exerts beneficial but only transient effects on mood in patients with a major depressive disorder (MDD). Though approximately 50 to 70% of depressed patients improve after sleep deprivation, the majority relapse after recovery sleep, some even after a short nap. One theoretical model postulates a critical period in the early morning hours where sleep is likely to induce a relapse, and nap studies indicate that sleep may be particularly 'depressogenic' at this time of day. A second model attributes the relapse to the release of non-REM sleep. We therefore compared the impact of an advanced sleep period (17:00-24:00 h) to a normal sleep period (23:00-06:00 h) on mood in patients who had responded to sleep deprivation. Less relapses into depression occurred after advanced sleep. Polysomnographic data showed that, as expected, normal sleep was characterized by a more pronounced improvement of sleep continuity and increased slow-wave sleep. The normal sleep group showed a stronger decrease in REM sleep density than the advanced sleep group compared with baseline. These data add to a growing body of evidence that the timing of sleep following successful sleep deprivation may be crucial for a stabilization of its antidepressant effect. Thus, avoidance of sleep during a "critical period' for more than a single night is necessary to provide a longer-lasting treatment modality.

Effect of morning and afternoon naps on mood after total sleep deprivation in patients with major depression

In 30 depressed patients who had responded to total sleep deprivation therapy, morning naps led more frequently to relapses into depression than did afternoon naps. Longer naps were less detrimental than shorter ones, and there was no significant relationship between the effect of a nap on mood and its content of slow-wave-sleep. The amount of the rapid eye-movement sleep, too, was unrelated to clinical nap effects. Thus, some of the current theories on the relationship between sleep and depressive symptomatology are not supported by the data. Our results demonstrate the importance of nap timing, suggesting a circadian variation of propensity to relapse into depression.