Phase advance of the circadian sleep-wake cycle as an antidepressant

A review of acute treatments for bipolar depression

Bipolar patients generally spend much more time in the depressed phase of their illness than the manic phase, and there are many more bipolar type II and bipolar spectrum disorder patients than there are bipolar type I. Additionally, there is a significant risk of suicide in bipolar patients when depressed. The treatment of the depressed phase of bipolar disorder is therefore a matter of some priority. Here, we review current evidence supporting the use of five groups of treatments: anti-depressants; lithium; anti-convulsants (valproate, and carbamazepine, lamotrigine, gabapentin); anti-psychotics; and other treatments (electroconvulsive therapy, benzodiazepines, sleep-deprivation, and dopamine agonists). From this review, it is apparent that the literature regarding the treatment of bipolar depression is significantly limited in several key areas. Nonetheless, from the evidence currently available, the treatments with the best evidence for efficacy are selective serotonin reuptake inhibitors (SSRIs) and lamotrigine. There is also some evidence in favour of bupropion and moclobemide. Although lithium and olanzapine monotherapies can also be beneficial, they appear less efficacious than antidepressants. One of the major concerns about treatment with antidepressants has been the risk of precipitating a switch into mania. However, recent studies suggest that, if a mood stabilizer and antidepressant are given concurrently, then the risk of switching is minimized. There is also recent evidence for an independent antidepressant action for at least one atypical antipsychotic. Therefore, the conclusion from this review, in contrast to previous suggestions, is that a combination of an atypical antipsychotic and either an SSRI or lamotrigine may provide a useful first-line treatment for depressed bipolar disorder patients. Further research is clearly required to examine this approach and compare it with other possible treatment options.

REM sleep reduction, mood regulation and remission in untreated depression

The contribution of increased rapid eye movement (REM) pressure through repeated, mild, reduction of (REM) sleep to remission from untreated depression was studied over a 5-month period in 20 depressed and 10 control volunteers. Sixty percent of the depressed subjects were in remission at the end of the study. Sixty-four percent of the variance in remission could be accounted for by four variables: the initial level of self-reported symptoms, the reported diurnal variability in mood, the degree of overnight reduction in depressed mood following interruptions of REM sleep and the quality of dream reports from these awakenings. Increased REM pressure is beneficial for those who are able to construct well-organized dreams.

Average sunrise time predicts depression prevalence

OBJECTIVE

Folk wisdom has it that early rising is associated with being "healthy, wealthy and wise." A physiologic explanation may be Wiegand's "Depressiogenic Theory of Sleep," which posits that excessive REM sleep causes depression. Sleeping late increases REM sleep, and thus may increase depression risk. Published depression prevalence research does not use arising time, but average sunrise time (AST) for cities might serve as an analogue for arising time. Two studies of depression prevalence in urban populations, the EURODEP Programme, which measured geriatric depression in nine European cities, and the Epidemiologic Catchment Area (ECA) study of five US centres, have so far lacked satisfactory explanations for the striking differences in depression prevalence between cities. It was hypothesized that differences in rising times between cities, as determined by AST, could explain the variability in depression prevalences.

METHODS

Correlations were calculated for published depression prevalences from the EURODEP and ECA studies, and AST for each site.

RESULTS

For both studies, depression prevalences are significantly correlated with AST, with later sunrise (corresponding to earlier arising times in relation to sunrise) associated with lower depression prevalence.

CONCLUSIONS

The hypothesis that later rising from sleep is associated with increased depression was supported. The findings also suggest that a city's depression prevalence could be reduced by simple public health measures to manipulate AST, such as going to Daylight Saving Time (DST) year-round or shifting time-zone boundaries. For individuals, getting up earlier from sleep may be helpful in depression.

Mutation screening of the human period 2 gene in bipolar disorder

We tested whether the human period 2 gene (hper2), one of the essential components of the circadian oscillator, might have influence on bipolar disorder. We screened 88 bipolar disorder patients and 127 controls, all of Japanese origin. Screening in the casein kinase I epsilon (CKIepsilon) binding region of hper2, which was previously reported in familial advanced sleep-phase syndrome patients, with polymerase chain reaction amplification revealed four polymorphisms. One of the four polymorphisms had an amino acid substitution of a serine at 662 with a glycine (S662G). The frequencies of the S662G allele and genotypes on patients with bipolar disorder were very low and had no difference from those in controls. Polymorphism on the CKIepsilon binding region of hper2 gene which was previously reported, is unlikely to play an important role in the development of bipolar disorder.

SB-258741: a 5-HT7 receptor antagonist of potential clinical interest

Recently, a series of 5-HT7 receptor antagonists have been developed (24,29,36,68). Among them SB-258741, R-(+)-1-(toluene-3-sulfonyl)-2-[2-(4-methylpiperidin-1-yl)ethyl]-pyrrolidine, (compound "13" in 36,37) was one of the most potent and specific compounds. Due to a lack of specific ligands the pharmacology of 5-HT7 receptor antagonists is still relatively unexplored. It has been suggested, however, that 5-HT7 receptor ligands could be useful in the therapy of various disorders such as sleep disorders, schizophrenia, depression, migraine, epilepsy, pain, or memory impairment. Many of these conceivable indications are not supported by pharmacological data. It is, therefore, of particular interest to review the data generated from studies of one of these most potent and specific 5-HT7 receptor antagonists, SB-258741, with a goal of testing the validity of the proposed clinical indications. In this review, the author describes pharmacology of this compound in order to define its potential clinical use. The available safety pharmacology data are discussed in an attempt to predict potential side effects of specific 5-HT7 receptor antagonists.

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 phase advance and lithium to sustain the antidepressant effect of total sleep deprivation in bipolar depression: new findings supporting the internal coincidence model?

Recent European studies suggested that sleep phase advance (SPA) could sustain the effects of total sleep deprivation (TSD) both with or without a combined antidepressant drug treatment. Previous studies by our group showed that an ongoing lithium treatment could enhance and sustain the effect of repeated TSD. In the present study we studied the effect of a single TSD followed by 3 days SPA (beginning with sleep allowed from 17:00 until 24:00, with daily shiftbacks of 2 h) in consecutively admitted bipolar depressed inpatients who were taking a chronic lithium salts treatment (n=16) or who were devoid of psychotropic medications (n=14). Changes in mood during treatment were recorded with self administered visual analogue scales and with Hamilton rating scale for depression. Results showed that SPA could sustain the acute antidepressant effect of TSD, and that lithium enhanced the effect of the chronobiological treatment. According to the internal coincidence model, the better clinical effects observed in lithium-treated patients could be due to the phase delaying effect of lithium on biological rhythms, leading to a better synchronization of biological rhythms with the sleep-wake cycle.

Is seasonal affective disorder a disorder of circadian rhythms?

Seasonal affective disorder (SAD) is a form of depression that starts in the fall and ends in the spring. This article reviews existing theories about the relationship between circadian rhythms and the disorder. Recent research indicates that as with pharmacologic antidepressants, at least 2-4 weeks are needed to demonstrate the effectiveness of bright-light therapy compared to placebo. The response to such treatment is strongest with precisely timed light exposure: treatment is optimal during the morning hours when the circadian system is susceptible to phase advance. Such clinical improvement is correlated with the magnitude of the phase shift induced. These observations suggest a model of circadian function in SAD and provide important guidelines for its treatment.

Is self-reported morbidity related to the circadian clock?

Morningness and eveningness preference, an endogenous component of the circadian clock, is characterized by an interindividual difference in circadian phase and requires of humans a specific timing of behavior. The biological rhythms of morning and evening types are consequently phase shifted with fixed socioeconomic constraints. The impact of this phase shift on health is widely debated. The purpose of the authors' study was to determine the influence of morningness/eveningness preference on self-reported morbidity and health in an active population. A total of 1165 nonshift workers of the French national electrical and gas company, enrolled in the GAZEL cohort and aged 51.3+/-3.3 years, were included in this study. They replied by mail with a completed questionnaire, including morningness/eveningness preference, self-reported morbidity, subjective sleep patterns, and daytime somnolence and sleeping schedules for 3 weeks, during the spring of 1997. Annual self-reported health impairments were assessed with the annual general questionnaire of the GAZEL cohort for 1997. After adjustment for age, sex, and occupational status, morningness-like and eveningness-like participants reported a specific worse self-reported morbidity. Whereas morningness was associated with worse sleep (p = 0.0001), eveningness was associated with feeling less energetic (p = 0.04) and physical mobility (p = 0.02). These relationships were observed even in good sleepers, except for physical mobility. After adjustment for confounding variables, eveningness-like participants reported more sleep (p = 0.0004) and mood (p = 0.00018) disorders than morningness-like participants. Morningness/eveningness preference was related to specific chronic complaints of insomnia: morningness was related with difficulty in maintaining sleep (p = 0.0005) and the impossibility to return to sleep in the early morning (p = 0.0001) (sleep phase-advance syndrome); eveningness was related to difficulty in initiating sleep (p = 0.0001) and morning sleepiness (p = 0.0001). In good sleepers, morningness was related with sleep phase-advance syndrome (p = 0.0001) and eveningness with morning sleepiness (p = 0.0001). In conclusion, the expression (phase advance or delay) of the circadian clock could be related to worse self-reported morbidity and health. These findings must be verified by further epidemiological studies, but they suggest that the impossibility to return to sleep in the early morning is not only associated with age.

Sleep in depression and sleep deprivation: a brief conceptual review

Risk factors for somnipathies are psychological stress or psychiatric illness. More severe sleep difficulties have been found to be clearly related to psychiatric illness such as depression and phobias, as well as to addiction. Somnipathies can objectively be identified by means of polygraphy. Overall, polysomnographic measures in patients with affective disorders differ most frequently and significantly from those in normal control subjects. Persistent sleep disturbances are associated with significant risk of both relapse and recurrence in mood disorders and an increased risk of suicide. In addition to changes in sleep architecture, patients with major depression show profoundly altered patterns of nocturnal hormone secretion, possibly through mechanisms that link regulation of sleep with neuroendocrine activity. Basic and clinical approaches of sleep research established neurobiological models into the underlying pathophysiology associated with psychiatric disorders.

Slow-wave activity in NREM sleep: sex and age effects in depressed outpatients and healthy controls

The amplitude and time course of slow-wave activity (SWA) during NREM sleep were compared in 76 outpatients with depression and 55 healthy control subjects. Lower SWA amplitude was evident in the depressed group, especially among depressed men. For the most part, significant differences between patients and control subjects were restricted to the first NREM period and only in those 20-30 years of age. Significant age-related declines in SWA amplitude were evident in control subjects but not in depressed patients. In addition, sex differences in the depressed group were twice as large as those seen in control subjects. The time course of SWA amplitude, presumed to reflect homeostatic sleep regulation of SWA, was only abnormal in depressed men with lower accumulation and slower dissipation over NREM sleep. Depressed women showed no evidence of an abnormal SWA time course. Furthermore, no sex differences in the time course of SWA were evident in control subjects, and age-related changes in this aspect of regulation were not striking in any group. Thus, the amplitude of SWA showed strong age effects in healthy individuals but not in those with MDD whereas the time course showed very subtle age effects. It was suggested that men, but not women, with MDD show impaired SWA regulation that is evident from 20 to 40 years of age. These findings provide further support that the pathophysiology of depression differs for men and women and suggest that maturational effects on SWA in depression differ from those observed in healthy individuals.

Sleep-wake cycle, sleep-related disturbances, and sleep disorders: a chronobiological approach

There is convincing evidence that the functions of sleep include restoration of brain energy storage and memory consolidation. The circadian timing system (CTS) is involved in the daily variation of almost any physiological and psychological variable evaluated thus far. Disturbances of the CTS can be clinically observed by their influence on the sleep-wake cycle, hormones, body temperature, and locomotor activity. This article reviews the basic mechanisms of circadian rhythm sleep disturbances, names the applicable diagnostic tools and specific therapeutic strategies, and thereby hints at the impact of circadian rhythm sleep disturbance on psychiatric disorders, especially disorders of affect and cognition. In light of the preventive, diagnostic, and therapeutic tools now available, a new round of chronobiological studies in psychiatry seems justified, promising, and necessary.

Ultradian rhythms and temporal coherence in sleep EEG in depressed children and adolescents

BACKGROUND

It has been suggested that a primary ultradian (80-120 minute) rhythm disturbance in EEG underlies sleep abnormalities in adults with depression. The present study evaluated ultradian rhythm disturbances in childhood and adolescent depression.

METHODS

Sleep macroarchitecture and temporal coherence in quantitative EEG rhythms were investigated in 50 medication-free outpatients with major depression (25 children and 25 adolescents) and 15 healthy normal controls (5 children and 10 adolescents).

RESULTS

Few of the macroarchitectural measures showed significant group effects. In fact, age and sex effects were stronger than disease-dependent components. Temporal coherence of EEG rhythms during sleep did differentiate those with MDD from controls. Both depressed children and adolescents had lower intrahemispheric coherence, whereas interhemispheric was only lower in depressed adolescents in comparison with controls. Gender differences were evident in adolescents, but not children, with MDD with lowest interhemispheric coherence in adolescent girls.

CONCLUSIONS

These findings are in keeping with increased risk for depression in females beginning at adolescence and extending throughout adulthood. It was suggested that low temporal coherence in depression reflects a disruption in the fundamental basic rest-activity cycle of arousal and organization in the brain that is strongly influenced by gender.

Effects of melatonin on the quality of life in patients with delayed sleep phase syndrome

OBJECTIVE

The purpose of this study was to compare health-related quality of life of delayed sleep phase syndrome (DSPS) patients with a random Dutch sample and four samples of patients with other chronic conditions. We also investigated the effectiveness of treatment with 5 mg of melatonin on the quality of life of DSPS patients.

METHODS

Forty-three DSPS patients completed a quality-of-life questionnaire (Medical Outcome Study Short Form-36 [MOS SF-36] health survey) just before and 2-9 months after participation in a clinical trial involving the administration of melatonin. Scores were compared with responses to the same survey by a random Dutch sample and by patients with sleep apnea, clinical depression, migraine, and osteoarthritis.

RESULTS

MOS SF-36 scales scores were significantly lower in DSPS patients relative to age- and gender-adjusted norms for the Dutch sample. Some health dimensions were more affected, and others less affected, by DSPS compared with the other chronic conditions. Melatonin treatment improved all scales except the scale "role due to emotional problems."

CONCLUSION

DSPS has a unique significant quality-of-life burden that seems to be improved by treatment with melatonin.

Sleep deprivation in depression: what do we know, where do we go?

Manipulations of the sleep-wake cycle, whether of duration (total or partial sleep deprivation [SD]) or timing (partial SD, phase advance), have profound and rapid effects on depressed mood in 60% of all diagnostic subgroups of affective disorders. Relapse after recovery sleep is less when patients are receiving medication; it may be prevented by co-administration of lithium, pindolol, serotonergic antidepressants, bright light, or a subsequent phase advance procedure. Diurnal and day-to-day mood variability predict both short-term response to SD and long-term response to antidepressant drug treatment. These mood patterns can be understood in terms of a "two-process model of mood regulation" based on the model well established for sleep regulation: the interaction of circadian and homeostatic processes. The therapeutic effect of SD is postulated to be linked to changes in disturbed circadian- and sleep-wake-dependent phase relationships and concomitant increase of slow-wave-sleep pressure; additionally, SD-induced sleepiness may counteract the hyperarousal state in depression. This model has the advantage of providing a comprehensive theoretical framework and stringent protocols ("constant routine," "forced desynchrony") to dissect out specific disturbances. Many aspects tie in with current serotonergic receptor hypotheses of SD action. A treatment inducing euthymia in severely depressed patients within hours is an important therapeutic option that has come of age for clinical use.

Relationship between social rhythms and mood in patients with rapid cycling bipolar disorder

Disruptions in the sleep-wake cycle frequently characterize affective illness and have led to a number of theories linking sleep-wake and/or circadian rhythm disturbance to affective illness. Recently, researchers have expanded these chronobiological theories to include the role of lifestyle regularity, or daily social rhythms. In this study, the Social Rhythm Metric (SRM) was used to explore the relationship between social rhythms and mood in patients with rapid cycling bipolar disorder and to compare the social rhythms of patients with those of healthy control subjects. Patients' SRM scores and activity level indices were significantly lower than those of control subjects. In addition, the timing of five, mostly morning, activities was phase delayed in patients compared to control subjects. Patients also demonstrated a phase delay in the timing of morning activities during depression compared to hypomania or euthymia. The phase changes in the timing of morning activities are consistent with other data implicating morning zeitgebers in the pathophysiology of rapid cycling bipolar disorder.

Molecular cloning and characterization of the human CLOCK gene: expression in the suprachiasmatic nuclei

The Clock gene is an essential regulator of circadian rhythms. It encodes a member of the basic helix-loop-helix/PER-ARNT-SIM family of transcription factors known to play a central role in the control of diverse cellular events. Previously we described the functional identification and molecular isolation of the Clock gene in the mouse, its interaction with the BMAL1 protein, and the role of this complex as a transcriptional activator in the circadian pacemaker. Here, we report the cloning, exon organization, chromosomal location, and mRNA expression of the human CLOCK gene. The coding sequence of human CLOCK extends for 2538 bp and is 89% identical to its mouse ortholog; its deduced amino acid sequence is 846 residues long and is 96% identical to mouse CLOCK. Radiation hybrid mapping localized human CLOCK to the long arm of human chromosome 4 (4q12). Direct sequencing of a genomic CLOCK clone indicated that the coding sequence of human CLOCK extends over 20 exons and that its intron/exon organization is identical to that of the mouse ortholog. Northern blot analysis indicated widespread expression of two major transcripts of 8 and 10 kb, and in situ hybridization of human brain tissue revealed elevated expression of CLOCK mRNA in the suprachiasmatic nuclei, the locus of circadian control in mammals, and in the cerebellum. Comparison of cDNA clones revealed two single nucleotide polymorphisms in noncoding sequence flanking the CLOCK open reading frame. The central role of Clock in the organization of circadian rhythms suggests that it will be a useful candidate gene for genetic analyses of disorders associated with dysfunction of the circadian system.

An analysis of the "eveningness-morningness" dimension in "depressive" college students

BACKGROUND

Circadian variability in depression has not been well characterized with respect to the "eveningness-morningness" dimension.

METHODS

The "eveningness-morningness" dimension, as measured by the Home and Ostberg questionnaire, was examined among a student population (n = 1617) that was named as "depressive". Three depression scales (BDI, GDS-SF, and CESD) were used to determine "depressiveness". The Horne and Ostberg questionnaire was used to measure the degree of "eveningness-morningness". It was hypothesized that there would be negative and significant correlations between the scores on the Horne and Ostberg questionnaire and the depression scales. Consequently, it was expected that there would be a significantly higher number of evening types than the morning types among the participants identified as "depressives".

RESULTS

There were significant, negative correlations between the Horne and Ostberg questionnaire scores and the responses on the 3 depression scales (for BDI r= -.174, GDS-SF r= -.182, CESD r = -.176, all p < .001). Also, a significantly higher incidence of evening types than of the morning types among the "depressive" students was found (chi2 = 11.18, p < .01).

LIMITATIONS

It is uncertain to what extent these data generalize to clinical populations.

CONCLUSIONS

"Depressive" college students are more likely to be evening types.

Treatment of rapidly cycling bipolar patient by using extended bed rest and darkness to stabilize the timing and duration of sleep

BACKGROUND

The modern practice of using artificial light to extend waking activities into the nighttime hours might be expected to precipitate or exacerbate bipolar illness, because it has been shown that modifying the timing and duration of sleep can induce mania in susceptible individuals. With this possibility in mind, we treated a patient with rapidly cycling bipolar illness by creating an environment that was likely to increase and to stabilize the number of hours that he slept each night.

METHODS

We asked the patient to remain at bed rest in the dark for 14 hours each night (later this was gradually reduced to 10 hours). Over a period of several years, his clinical state was assessed with twice-daily self-ratings, once-weekly observer ratings, and continuous wrist motor activity recordings. Times of sleeping and waking were recorded with sleep logs, polygraphic recordings, and computer-based event recordings.

RESULTS

The patient cycled rapidly between depression and mania and experienced marked fluctuations in the timing and duration of sleep when he slept according to his usual routine, but his sleep and mood stabilized when he adhered to a regimen of long nightly periods of enforced bed rest in the dark.

CONCLUSIONS

Fostering sleep and stabilizing its timing by scheduling regular nightly periods of enforced bed rest in the dark may help to prevent mania and rapid cycling in bipolar patients.

Testing the hypothesis of a circadian phase disturbance underlying depressive mood in nonseasonal depression

In a crossover design, 8 nonseasonal depressed subjects, selected on the presence of diurnal mood variations, and 8 sex- and age-matched controls were exposed to dim light (< 10 lux) in the evening (18:00-21:00 h) and bright light (2500 lux) in the morning (ML, 6:00-9:00 h), to dim light in the morning and bright light in the evening (EL), or to dim light both in the evening and in the morning (DL) during 3 consecutive days in each of these conditions. There were no initial phase differences between depressed and healthy subjects in the timing of dim light melatonin onset, sleep termination, and body temperature. The phase shifts after EL and ML in both healthy and depressed subjects were as expected on the basis of a human phase response curve. On average, there was no therapeutic effect of the light exposure in the depressed patients. Two patients improved, but these effects do not seem to be related to shifts in the circadian system.

Electroconvulsive therapy increases circadian amplitude and lowers core body temperature in depressed subjects

BACKGROUND

Reduced amplitude of the circadian temperature rhythm and elevated nocturnal body temperature normalize after successful pharmacotherapy of major depression.

METHODS

Core body temperature was continually monitored in three groups: a) 6 depressed patients before an electroconvulsive therapy (ECT) course and b) after an ECT course; and c) 6 healthy, sex-matched controls of similar age.

RESULTS

The 24-hour profile of temperature was significantly different in patients pre-ECT than in patients post-ECT or in controls. Post-ECT subjects and controls manifested 24-hour profiles similar to one another. Circadian temperature rhythm amplitude increased after ECT. The mean asleep and mean 24-hour temperatures were significantly higher in patients pre-ECT than post-ECT and controls.

CONCLUSIONS

We find that ECT restores a disrupted circadian temperature rhythm in depressed patients.

Sleep and mood disorders

Mood disorders are found in one-third to one-half of patients with chronic sleep problems. Likewise, most patients with mood disorders experience insomnia, but a minority obtain significantly increased amounts of sleep. Although mood disorders cause significant morbidity and mortality, they often go undiagnosed. Attention to sleep complaints could lead to better identification of mood disorders. Management of sleep problems in patients with mood disorders should focus on treating underlying mood disorders with attention to the nature of the sleep complaint. Patients with depression show characteristic abnormalities in sleep continuity, slow-wave sleep and REM sleep patterns. Differences in sleep patterns cannot reliably distinguish patients with depression from those with other psychiatric disorders, but sleep changes may provide a window on neurobiologieal abnormalities in depression.

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.

Clinical applicability of therapeutic sleep deprivation

The short-term antidepressive effect of single sleep deprivation (SD) treatment has been unanimously confirmed in a large number of studies. SD is most effective in patients with a major depressive episode (with melancholic features) but is also promising in other depressed patients suffering from vital symptoms and exhibiting a typical diurnal variation in mood (with morning low) irrespective of the type of depression. The SD modification of choice is partial SD in the second half of the night. SD is an easily applied treatment measure that is free from serious side effects. The tolerability can be improved further by performing SD in groups. SD is to be administered repeatedly rather than once and combined with pharmacotherapy. The mechanism of action underlying therapeutic SD has not yet been discovered. However, for its favorable influence on the overall antidepressive treatment outcome, SD should not only be applied in therapy-resistant depression but is to be looked upon as part of the standard antidepressive somatotherapy.

Relationship between sleep and mood in patients with rapid-cycling bipolar disorder

The relationship between sleep and mood was examined in a longitudinal, naturalistic data set derived from out-patients with rapid-cycling bipolar disorder. Eleven patients completed daily self-ratings of mood and sleep logs for 18 months. Using logistic regression with autoregressive terms, we examined the effect of prior sleep (sleep duration, time of sleep onset, and time of wake onset) on the probability of being in a depressed, manic, or hypomanic episode on one or more subsequent days. Of the three sleep parameters, decreased sleep duration was the best predictor of mania or hypomania the next day, followed by wake onset time. The association between sleep duration and subsequent mood was less consistent for depression than for mania or hypomania. Four of the patients showed no relationship between mood and any of the sleep variables measured. These results reinforce the importance of monitoring, and perhaps controlling, sleep duration and wake onset time in at least some patients with rapid-cycling bipolar disorder.

Treatment-resistant bipolar depression

Patients with treatment-resistant bipolar depression require careful management, which takes into account the life-threatening potential of their depression and the risk of iatrogenic mania. Because there are few data specific to treatment of bipolar depression, much of the approach to bipolar depression is derived from experience with unipolar depression. There are, however, important differences between these two illnesses. Compared with patients with unipolar illness, patients with bipolar depression more likely experience antidepressant benefit from mood-stabilizing medication and, therefore, avoid the risks of antidepressant medication. Treatment of comorbid anxiety and substance abuse improves response. The risk of treating bipolar patients can be reduced but not avoided. Improved outcome may be achieved by careful assessment, prospective mood charting, and attempts to taper antidepressant medications after an appropriate continuation phase.

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.

Circadian rhythms and the pharmacology of affective illness

The chronic effects of antidepressant drugs (ADs) on circadian rhythms of behavior, physiology and endocrinology are reviewed. The timekeeping properties of several classes of ADs, including tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, serotonin agonists and antagonists, benzodiazepines, and melatonin are reviewed. Pharmacological effects on the circadian amplitude and phase, as well as effects on day-night measurements of motor activity, sleep-wake, body temperature (Tb), 3-methoxy-4-hydroxyphenylglycol, cortisol, thyroid hormone, prolactin, growth hormone and melatonin are examined. ADs often lower nocturnal Tb and affect the homeostatic regulation of sleep. ADs often advance the timing and decrease the amount of slow wave sleep, reduce rapid eye movement sleep and increase or decrease arousal. Together, AD effects on nocturnal Tb and sleep may be related to their therapeutic properties. ADs sometimes delay nocturnal cortisol timing and increase nocturnal melatonin, thyroid hormone and prolactin levels; these effects often vary with diagnosis, and clinical state. The effects of ADs on the coupling of the central circadian pacemaker to photic and nonphotic zeitgebers are discussed.

Treatment of acute bipolar depression: a review of the literature

OBJECTIVE

Our goal was to ascertain the efficacy of various antidepressant treatments for acute bipolar depression.

METHOD

English articles that reported on the efficacy of antidepressant treatments in bipolar depression were located by computerized Medline and manual search. These studies were systematically reviewed and response rates for each treatment were computed.

RESULTS

The available data suggest that mood stabilizers, MAOIs, cyclic antidepressants, and ECT are all effective in treating bipolar depression. All antidepressant treatments with the exception of mood stabilizers have been reported to induce a manic/hypomanic switch.

CONCLUSIONS

It is recommended that mood stabilizers may be the first step of treatment, followed by the addition of an antidepressant, especially a cyclic antidepressant. The specific symptoms profile of individual patients, such as anergic or psychotic features, may indicate more specific treatment options. ECT is an important measure for those who are pharmacotherapy-resistant or psychotic.

Treatment of delayed sleep phase syndrome

Delayed sleep phase syndrome (DSPS) is a common but little reported cause of severe insomnia. Affected individuals complain of difficulty falling asleep and difficulty awaking at socially acceptable hours. It results from a dysregulation of the circadian sleep-wake cycle. DSPS presents in clinically heterogenous ways as modulated by motivation, psychopathology, drug status, and treatment compliance factors. Patients respond variably to the range of possible treatments. Bright light treatment potentially corrects the circadian abnormality of DSPS. Other treatments reported to relieve some DSPS patients include schedule shifts, drugs, and vitamin and hormone treatments. The safety and efficacy of light treatment have not been conventionally defined, but available information suggests that it is ophthalmologically safe. At present, DSPS must be managed empirically by various methods.

An integrative analysis to sleep functions

Various studies suggest that some sleep functions, especially some slow wave sleep functions, are indispensable in mammals and related to brain regulation. It has been proposed that two of these functions are the adjustment of emotional balance and the processing of acquired emotional memories. During waking, the gradual accumulation of various randomly learned emotional memories in the limbic structures would inevitably imbalance and disorganize emotional behaviors. Although the emotional balance can be restored during waking by the ascending NA, DA, ACh and 5-HT systems, their roles in memory retention and emotional regulation may sometimes be dissociated and their adjustment of the emotional balance can only be a transient effect. On the other hand, the function of slow wave sleep for emotional adjustment can be long-lasting and is in agreement with its function on the processing of emotional memories. As a result, these sleep functions become indispensable in preventing the emotional imbalance inevitably caused by the accumulation of emotional memories. The effects of rapid eye movement sleep on memory and emotional regulation are just opposite to those of slow wave sleep. Low vigilance is required as premise for sleep to accomplish these indispensable functions.

Circadian rhythm of vital signs, norepinephrine, epinephrine, thyroid hormones, and cortisol in schizophrenia

Changes in the circadian rhythmicity in vital signs, catecholamines, thyroid hormones, and cortisol have been observed in psychiatric disorders, most notably in depression. With respect to schizophrenia, the literature is scanty. We report here on the circadian parameter estimates of the vital signs, epinephrine, norepinephrine, triiodothyronine, thyroxine, thyroid stimulating hormone, and cortisol in the blood of 34 healthy subjects, 89 drug-free schizophrenic patients, and 25 neuroleptic-treated schizophrenic patients. The analyses are based on the cosine model to fit the experimental data. The circadian profiles of heart rate, blood pressure, and oral temperature are similar among schizophrenic patients and healthy subjects. Neuroleptic-treated patients have significantly higher MESORs (the daily mean) of serum norepinephrine and epinephrine than healthy subjects. The TSH MESOR is significantly lower in schizophrenic patients; the MESOR of triiodothyronine also shows a tendency to be nonsignificantly lower in schizophrenic patients compared with control subjects. The circadian serum thyroxine and cortisol profiles are similar in the three groups. The data show that the circadian profiles of vital signs in drug-free chronic schizophrenic patients who are not chronically hospitalized are similar to those of healthy subjects and that the increase in serum catecholamines and the apparent lowering in some thyroid indices might induce a down-regulation in the noradrenergic receptor system that could contribute to the pathophysiology of schizophrenia.

Sleep regulation: physiological models and hypotheses

The elucidation of sleep regulation is not an easy task. On one side, there is a multitude of solid yet disparate data, on the other side, the topic is tempting for engaging in wild speculation, particularly with respect to the functions of sleep. Models may exert a moderating influence by mediating between the two extremes. However, also they navigate between the risk of banality in reformulating the obvious, and the peril of fancy in losing touch with empirical reality.

Treating depression with sleep deprivation and consecutive sleep phase advance therapy

The common treatment modalities for depression, i.e. pharmacotherapy and psychotherapy have the significant disadvantage of at least a three- to four-week time lag between initiation of treatment and amelioration of mood. Total sleep deprivation (TSD) in contrast, leads to an immediate antidepressant effect in 60% of the patients. However, it has gained only little clinical relevance as usually the improvement is only transient and almost regularly reversed by the next nights of sleep. A procedure preserving the antidepressive effect of sleep deprivation would therefore be of high clinical relevance.

Psychiatric morbidity in travelers to Honolulu, Hawaii

To investigate the phenomenon of acute psychiatric decompensation in travelers, charts of all psychiatric-emergency patients with a history of recent travel involving time-zone changes were reviewed at a major medical center in Honolulu, HI. Charts of a control group with no history of travel were also reviewed. Significantly more travelers than controls showed symptoms of depression and mania (P < .012). East-bound travelers were significantly more likely to show symptoms of mania than controls (P < .001). In an eastbound-versus-westbound comparison, significantly more eastbound travelers showed symptoms of mania, whereas significantly more westbound travelers showed symptoms of depression (P < .05). These findings support the phase-advance hypothesis of depression. Psychosocial and biologic factors that may contribute to psychiatric decompensation in travelers are discussed.

Seasonal affective disorder in a tropical country: a case report

Seasonality and affective disorders in the Southern Hemisphere were investigated in populations living in latitudes (40 degrees S) equivalent to those of the studies conducted in the Northern Hemisphere. The authors describe a patient with bipolar II affective disorder who was living in a low-latitude area (São Paulo, latitude: 23 degrees 39' S). The patient experienced five episodes of affective disorder that began in the summer and were characterized by symptoms typical of an autumn-winter depression. During the last two depressive episodes, the symptoms remitted after a 4-week course of evening light therapy. The case calls attention to the possibility that seasonality may influence the natural history of affective disorders even in lower latitude regions.

Effects of acute and chronic treatment with trazodone, an antidepressant, on the sleep-wake activity in rats

Rats were treated with trazodone (2.5 or 10 mg kg-1) twice a day (at light and dark onset) for 11 days, after chronic injection of physiological saline. The sleep-wake activity was recorded for 24 h on the baseline day (saline), on trazodone days 1, 5 and 11, and also on day 12, when physiological saline was injected again (withdrawal day). Trazodone administration increased non-REM sleep. The enhancement of non-REM sleep was dose-related and more pronounced during the dark cycle. The promotion of non-REM sleep was enhanced during the chronic treatment. There were no consistent changes in REM sleep. Spectral analysis of the EEG revealed an increase in slow-wave activity after administration of the high dose (10 mg kg-1) of the drug. It is concluded that trazodone, a clinically effective antidepressant, has a non-REM sleep-promoting effect. It is speculated that the promotion of sleep by trazodone may be mediated by serotonergic mechanisms.

Antidepressant and depressogenic drugs lack consistent effects on hamster circadian rhythms

The circadian wheel-running rhythm of golden hamsters was monitored during chronic oral treatment with four antidepressants and two potentially depressogenic agents. Desmethylimipramine shortened the circadian period (tau) by 0.1 hour. In contrast, clorgyline lengthened tau by 0.1 hour and delayed light-synchronized wheel-running rhythms by 1.4 hour. Phenelzine, fluoxetine, clonidine, and propranolol did not significantly alter light-entrained phase or free-running period over a range of doses. Other rhythm parameters were also unaffected by antidepressant or depressogenic drugs. These data suggest that mood-altering drugs do not consistently influence circadian rhythms in the hamster.

Nocturnal and circadian body temperatures of depressed outpatients during symptomatic and recovered states

Forty-one recurrent unipolar depressed outpatients were studied at baseline (symptomatic period) and at recovery. Rectal temperatures were measured continuously between 1800h and 0600h on 2 successive nights at each time point. In those 24 patients who recovered after receiving interpersonal psychotherapy (IPT) alone ("psychotherapy responders") and who thus remained drug-free throughout, there was no difference in nocturnal body temperatures between baseline and recovery time points. Moreover, nocturnal temperature patterns appeared to be very similar to those of a healthy contrast group (n = 17). The contrast group was not matched for age and gender with the patient group, though, so the comparison was only suggestive. At baseline, those recovering after psychotherapy alone (n = 24) did not differ from those eventually failing to respond to IPT and requiring medications to achieve recovery ("medication responders") (n = 17). Medication responders did show some baseline versus recovery differences in nocturnal temperatures, but these may possibly have been a function of the medications used. At recovery, a subset of 19 psychotherapy responders and 13 medication responders underwent an "unmasking" experiment involving 36 hours of wakeful bedrest. In the resulting endogenous temperature rhythms, there was no evidence of any reliable differences between the psychotherapy responder and medication responder patient groups. Both groups showed rhythms that were very similar to those of a healthy contrast group (n = 17), although, again, the contrast group was not matched for age or gender with the patient group. In conclusion, in measures of body temperature, at least, there appeared to be little evidence of circadian dysfunction in this group of recurrent outpatient depressives.

Rapid eye movement sleep disturbance in posttraumatic stress disorder

The subjective sleep disturbance in posttraumatic stress disorder (PTSD), including the repetitive, stereotypical anxiety dream, suggests dysfunctional rapid eye movement (REM) sleep mechanisms. The polysomnograms of a group of physically healthy combat veterans with current PTSD were compared with those of an age-appropriate normal control group. Tonic and phasic REM sleep measures in the PTSD subjects were elevated on the second night of recorded sleep. Increased phasic REM sleep activity persisted in the PTSD group on the subsequent night. During the study, an anxiety dream occurred in a PTSD subject in REM sleep. The results are consistent with the view that a dysregulation of the REM sleep control system, particularly phasic event generation, may be involved in the pathogenesis of PTSD. The finding of a specific disturbance of sleep unique to PTSD may have significant implications for the design of effective treatments for PTSD.

[Sleep and biological rhythms in depression. Changes caused by antidepressants]

Sleep in depression is characterized by an increase in the number and duration of awakenings, sleep instability, and SWS decrease. REM sleep occurs earlier. REMs density during the 1st REM period is higher than in normal controls matched in age. Accordingly, sleep in depression is similar to sleep in normal aging. Endogenous depression cannot be distinguished from other types of depression by means of polygraphic criteria. Sleep recordings at the beginning of tricyclic compound treatment could be predictive of clinical response to treatment. Sleep modifications induced by antidepressive drugs are reviewed. Sleep recordings enabled us to formulate several physiopathological hypotheses of depression mechanisms: cholinergic-aminergic hypothesis, phase advance, deficiency of process S. Other hypotheses are reviewed: flattening of a hypothetical circadian rhythm of arousal, depressogenic property of sleep in itself (or only of SWS) or timing delay for the start of sleep. A significant phase advance of biological rhythms (temperature, cortisol) is rarely found. A reduction in the amplitude of rhythms (temperature, TSH, melatonine) is more frequent.

Melatonin and hormonal changes in disturbed sleep during late pregnancy

Although sleep disturbance is commonly reported in pregnancy, there have been surprisingly few studies on the etiology of this condition. Since most hormones show circadian rhythmicity and maintain specific phase relationships with that of the sleep-wake cycle, it was of interest to establish whether sleep disturbances covaried with endocrine changes. This overnight study of pregnant women compared melatonin, cortisol, and prolactin secretion rhythms in six good sleepers and six poor sleepers. The groups were compared by ratios of the areas under the various hormonal curves. Significant differences in the cortisol/melatonin ratio were found between the poor sleeper group (lower values) and the good sleeper group (higher values). Nonsignificant trends, which might be expected to become significant with larger sample sizes, were found for decreased amplitude in the cortisol rhythm and increased amplitude in the melatonin rhythm in poor sleepers. The decreased amplitude of the cortisol rhythm in poor sleepers appeared to be due to a suppression of the early morning (0500-0800) rise. Prolactin levels were high and showed no rhythmicity in both groups. These differences may reflect changes in the circadian pacemaker system of poor sleepers, with increases in melatonin release being a response to counteract poor sleep.

Melatonin rhythms in seasonal affective disorder

We examined 24-hour melatonin rhythms from 20 patients with seasonal affective disorder (SAD) and 20 healthy volunteers. Patients and controls were individually matched for age, sex, and month of study. Plasma samples were taken at hourly intervals, and were assayed for melatonin by radio-immunoassay. The 24-hourly melatonin estimations for each individual were fitted to a cosine curve, and the significance of the curve fits was calculated. Two analyses were performed. In analysis 1 the following were calculated: (a) cosine fit, (b) significance of fits, (c) mean amplitude and acrophase (peak) and (d) mean melatonin levels. The curve fits were highly significant for all but three subjects (two patients, one control), but there were no significant differences in any measure between the two groups. In analysis 2 the comparisons were repeated and restricted to the 18 patients and 19 controls in whom there was a significantly significant melatonin rhythm. Again there were no significant differences between groups. These results suggest that the circadian rhythm of melatonin is not abnormal in SAD, and that the therapeutic effect of light in SAD is not mediated by phase shifts in melatonin secretion.