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

Clinical aspects of the melatonin action: impact of development, aging, and puberty, involvement of melatonin in psychiatric disease and importance of neuroimmunoendocrine interactions

During the last decade we have learned much on physiological changes in the secretion of the pineal hormone melatonin (MLT) in man. Reportedly, there is little or no MLT secreted before age 3 months. Then MLT production commences, becomes circadian, and reaches highest nocturnal levels at the age of 1-3 years. During all of childhood nocturnal peak levels drop progressively by 80% until adult levels are reached. This alteration appears to be the consequence of increasing body size in face of constant MLT production during childhood. The biological significance of this MLT alteration is presently unknown. Because of conceptual considerations, major depressive syndrome (MDS) and seasonal affective disorder (SAD) have been in the focus of pineal research for several years. Although in these disorders alterations in MLT levels could not be substantiated, light therapy, a consequence of this research, was discovered as an effective treatment for SAD and perhaps for MDS. In addition, there is some recent evidence for low MLT levels in schizophrenia. Finally, the potential effect of MLT in neuroimmunoendocrine interactions is presently explored. Reportedly, in vitro studies and animal experiments give evidence for a modulatory role of MLT in the immune response. However, the exact way of this possible action of MLT remains to be clarified. Clinical studies are too scant for a meaningful estimation of MLT's involvement in human neuroimmunoendocrine interactions.

Melatonin and sleep in humans

Early studies on the physiological effects of melatonin typically reported hypnotic 'side-effects'. Later studies, specifically addressing this action, failed to reliably replicate hypnotic effects using standard polysomnography. This difference may be related to differences in the basic physiological action of melatonin compared with more conventional hypnotics. It is suggested that melatonin exerts a hypnotic effect through thermoregulatory mechanisms. By lowering core body temperature, melatonin reduces arousal and increases sleep-propensity. Thus, in humans, one role of melatonin is to transduce the light-dark cycle and define a window-of-opportunity in which sleep-propensity is enhanced. As such, melatonin is likely to be an effective hypnotic agent for sleep disruption associated with elevated temperature due to low circulating melatonin levels. The combined circadian and hypnotic effects of melatonin suggest a synergistic action in the treatment of sleep disorders related to the inappropriate timing of sleep and wakefulness. Adjuvant melatonin may also improve sleep disruption caused by drugs known to alter normal melatonin production (e.g., beta-blockers and benzodiazepines). If melatonin is to be developed as a successful clinical treatment, differences between the pharmacological profile following exogenous administration and the normal endogenous rhythm should be minimized. Continued development as a useful clinical tool requires control of both the amplitude and duration of the exogenous melatonin pulse. There is a need to develop novel drug delivery systems that can reliably produce a square-wave pulse of melatonin at physiological levels for 8-10 hr duration.

Sleep deprivation in depressed adolescents and psychiatric controls

Up to 70% of depressed adults have an antidepressant response to sleep deprivation. To study the effects of sleep deprivation on depression severity and level of arousal in psychiatrically disturbed adolescents, we deprived 17 patients of sleep for 36 hours. Severity of depression and subjective arousal were assessed at baseline, during sleep deprivation, and after 1 night's recovery sleep. We found that severely depressed adolescents showed a significant decrease in depression severity, whereas depressed patients in remission and psychiatric controls worsened after sleep deprivation. Patients with depression in remission showed a significant decrease in subjective arousal after sleep deprivation. In contrast to findings in depressed adults, the effects of sleep deprivation persisted after 1 night of recovery sleep, and diurnal variation of mood did not predict response to sleep deprivation. These findings are consistent with those reported in the adult literature, and suggest a common psychophysiology between adult and adolescent depression.

The premenstrual syndrome--a reappraisal of the concept and the evidence

The Premenstrual Syndrome (PMS) remains a controversial issue. As a clinical concept it is surrounded by confusion. Attempts to establish a consensus definition have resulted in the majority of women seeking help for such problems excluded from the diagnosis. Furthermore, there is no consensus about how such problems should be treated, with a variety of methods being advocated usually on very uncertain scientific grounds. The issue also has its political implications; there are those who see PMS as a way of reducing the status of women, by linking the normal ovarian cycle to a phenomenon which, on the face of it, impairs women's ability to cope. Yet there are a substantial number of women who experience significant negative changes which vary with the menstrual cycle, and produce long-term effects on their well being and family relationship which can be serious. There is also a real possibility that recurrent perimenstrual mood changes of this kind may increase the likelihood of chronic depressive illness in susceptible individuals. In most respects the features of depression which occurs perimenstrually are essentially similar to those of major depressive disorder, except for the short duration and recurrent pattern. PMS, therefore, remains an issue not only of clinical importance, but of considerable potential relevance to our understanding of major depressive disorder, which is substantially more common in women of reproductive age than in their male counterparts. In this review the concept of PMS, and some prominent operational definitions of it, are critically evaluated; it is now questionable whether the concept, as currently applied, still carries any heuristic or clinical value. Some current theoretical and aetiological issues are considered: e.g. the role of the corpus luteum, the effects of hormonal regimes which block ovulation, such as oral contraceptives, and the possibility that cyclical mood change represents an entrained rhythm in the brain. The conclusions reached at this stage in the review lead to a 'paradigm shift' with the proposal of a three-factor model to account for the complexities of menstrual cycle-related problems.(ABSTRACT TRUNCATED AT 400 WORDS)

Disruption of social circadian rhythms in major depression: a preliminary report

While dysregulations of physiological circadian rhythms are common findings in depression and have been posited to be involved in the mediation of depressive episodes, only recently has the role of social circadian rhythms in the pathogenesis of depression been a focus of interest. The Social Rhythm Metric (SRM), designed to describe the regularity of a human subject's social circadian rhythms, was used in this study to compare the social rhythms of depressed patients with those of normal controls and to determine the relationship between SRM scores and depression severity. Depressed patients' SRM scores were significantly lower than those of normal controls. The SRM negatively correlated with scores on the Hamilton Rating Scale for Depression. Overall social activity was negatively correlated with a Hamilton item, social activity impairment. The results of this preliminary study support the hypothesis that social zeitgebers are disrupted in major depression.

Can non-REM sleep be depressogenic?

Sleep and mood are clearly interrelated in major depression, as shown by the antidepressive effects of various experiments, such as total sleep deprivation, partial sleep deprivation, REM sleep deprivation, and temporal shifts of the sleep period. The prevailing hypotheses explaining these effects concern the antidepressant potency of the suppression of either REM sleep or non-REM sleep. This issue is discussed in the light of present knowledge of the kinetics of non-REM sleep intensity, REM sleep production, and their interaction. Recent findings have led us to suggest that the suppression of non-REM sleep intensity is the common pathway in the set of experimental data on the antidepressant effects of sleep manipulations.

Rhythms and the pharmacology of lithium

Lithium is the treatment of choice for bipolar affective disorder (manic-depression) and is useful in other recurrent affective and nonaffective illnesses. This review discusses lithium's actions on period, phase, amplitude and coupling of biological rhythms that may relate to its therapeutic effectiveness. Alternatively, lithium might interact with environmental light to influence circadian rhythms by an action on the retina. The mechanisms responsible for lithium's chronopharmacological actions are not known, but cellular cations, phosphoinositide or adenylate cyclase second messenger systems, hormones and neurotransmitters may all be involved.

Seasonal affective disorder, Part II: Phototherapy, an expanded role of the psychosocial nurse

The integration of neurobiology into the research and practice of psychosocial nursing is an imperative for the decade of the 1990s. This substantial goal probably will be achieved through the completion of smaller endeavors. This article is intended to be one such contribution. The purpose of this article are threefold. First, it will introduce the psychosocial nurse to the characteristics of Seasonal Affective Disorder (SAD). This article also will provide the psychosocial nurse with the putative biological basis of SAD and phototherapy. Finally, specific information regarding the therapeutic application of bright light is provided.

The functions of sleep: further analysis

Most theories addressed to the functions of sleep are proposed primarily according to the results in one area of sleep research and may not be compatible with the results in other areas of sleep research. This paper provides a new theory regarding the functions of sleep by integratively analyzing different areas of sleep research. First, it concludes from the phylogenetic studies and other related sleep research that sleep in mammals has at least one obligatory function which cannot be accomplished during waking. It also shows that the synchronized sleep (SS) period plays a critical role in accomplishing the obligatory functions of sleep and that the obligatory functions of sleep are related to the brain. Then it points out that adjusting and reorganizing emotional behaviors is a very important function of SS. Finally, this theory suggests that the gradual accumulation of various randomly learned memories in the limbic structures would inevitably imbalance and disorganize emotional behaviors so that sleep should be developed in evolution to adjust and reorganize emotions and so that the functions of SS for memory and emotional regulation are the obligatory functions of sleep. Although phylogenetic studies suggest that (PS) may not play obligatory functions across all mammals, there is no doubt that, in tight correlation with SS, PS also plays very important roles in memory and emotion which, however, are different from the corresponding SS roles in those mammals possessing PS.

Sleep deprivation therapy

This review reports, with as much detail as possible, on the literature relating to therapeutic sleep deprivation (or induced-wakefulness therapy) since it was first described in 1971. The antidepressive effect of sleep deprivation has been substantiated by numerous studies. A series of clinical predictors of response to sleep deprivation are also described. Partial sleep deprivation late in the night is equivalent to total sleep deprivation in terms of therapeutic value and--because of its simpler application--can be regarded today as the sleep deprivation method of choice. The status of sleep deprivation in the overall treatment schedule for depressive disorders is discussed in detail. Numerous findings, some of them contradictory, have been published on the effect of sleep deprivation on biological variables. To date, no unequivocal explanation has been found for the mechanism of action of sleep deprivation.

Primary and secondary depression in alcoholism--clinical features and family history

One hundred thirty-six alcoholic inpatients were studied with regard to the association between alcoholism and depression. They fell into three groups: primary depression, secondary depression and non-depressive alcoholism. The main results obtained are as follows: (1) Depression was found in 46 patients (33.8%) in the present or past history; 13 were regarded as primary depression and 33 as secondary depression. (2) The clinical symptoms and the background of the primary group resembled those of endogenous depression. (3) The clinical features, including the duration of depressive episodes in the secondary depression group differed from those in the primary group. (4) No statistically significant differences were noted as to the rates of family-history of alcoholism and depression among the three groups. Clinical and biological differences between the primary and secondary groups were discussed on the basis of these results.

Diurnal rhythm of core body temperature is phase advanced in a rodent model of depression

We examined the diurnal rhythm of core body temperature in a strain of rats with an upregulated central muscarinic receptor system. The Flinders-Sensitive Line (FSL) was derived by selectively breeding rats for sensitivity to cholinergic agonists. When compared to control rats, the FSL rats showed a remarkably strong phase advance of the acrophase in body temperature during a standard light-dark schedule. Some patients with some types of depression also show phase advances in a number of circadian rhythms, including temperature. Our finding of a phase advance in a rodent model with a known upregulated muscarinic receptor system is compatible with both the phase advance and the muscarinic overdrive theories of depression. These findings also further validate the usefulness of the FSL rats in the study of depression.

Melatonin: a chronobiotic with anti-aging properties?

Recently, it has been reported that melatonin administration extends the lifespan of mice, a finding which supports previous research on the effects of pinealectomy and pineal extract administration. The prolongation of lifespan by melatonin has been interpreted in favour of an upregulation of the immune system as well as due to anti-stress properties of melatonin acting via the brain opioid system. In this paper we offer an alternative explanation of melatonin's anti-aging effect: the circadian pacemaker system has a diminished amplitude with age as indexed by a decrease in circulating melatonin levels. Stability of the circadian system correlates with its amplitude and loss of circadian amplitude produces lability which, in turn, leads to internal temporal disorder. Internal temporal disorder may be a precursor of disease states. Exogenous melatonin increases the amplitude of the circadian pacemaker system by feedback onto that system. The hypothalamic suprachiasmatic nuclei are thought to be the mammalian biological clock in the brain and have high concentrations of melatonin receptors. Therefore, melatonin administration in pharmacological doses may prevent aging symptoms by acting at the level of the circadian pacemaker's amplitude.

The effects of shifting sleep two hours within a fixed photoperiod

This study examined the effects of shifting the time of sleep within a constant photoperiod on the circadian rhythms of body temperature and melatonin secretion. Subjects lived under conditions of a long scotoperiod (dim light of less than 10 lux from 6 p.m. until 8 a.m.) for three weeks. In order to delineate dawn and dusk, subjects received one hour of bright light (2500 lux) before and after the scotoperiod (i.e., from 8 to 9 a.m. and from 5 to 6 p.m.). For the first week of the experiment they slept from 10 p.m. until 6 a.m. In the second week, sleep was advanced two hours; that is, subjects retired at 8 p.m. and arose at 4 a.m. The third week was a repeat of the first, resulting in a two-hour delay of sleep from week two to three. The six subjects who successfully completed this protocol had no significant changes in the timing of the body temperature minima and onset of secretion of melatonin. This indicates that the timing of allowed sleep has less of an immediate effect on circadian rhythms than the timing of the external light-dark cycle. The circadian effects of the timing of sleep may be due more to the light-dark cycle that is imposed by the sleep-wake cycle than from the timing of sleep itself.

The influence of physical activity and posture on the antidepressant effect of sleep deprivation in depressed patients

A possible role of the factors 'physical activity' and 'posture' in the antidepressant effect of a total night's sleep deprivation (TSD) was investigated in 30 patients with major depressive disorder. Fifteen patients underwent TSD under 'conventional' conditions, while the other 15 were kept in bed during TSD but were not permitted to sleep. There was no significant difference between the antidepressant effects of TSD in the two groups. This result suggests that it is wakefulness itself rather than changes in physical activity or posture that is involved in the mechanism of the antidepressant action of TSD.

Is winter depression a bipolar disorder?

Sixty-one winter depressive patients were evaluated for evidence of bipolar illness. Using the Schedule for Affective Disorders and Schizophrenia-Lifetime Version and the General Behavior Inventory, only nine (15%) could be considered bipolar. On prospective evaluation of patients during the summer following winter depression, few showed signs of manic or hypomanic symptoms. Also, few patients had a family history of bipolar illness. When patients were asked to evaluate symptoms of winter depression, lack of energy was found to be the most prominent feature of the syndrome.

Total and partial sleep deprivation in clomipramine-treated endogenous depressives

Improvement in depression after total sleep deprivation (TSD) is, as a rule, followed by relapse after subsequent ad libitum sleep. This study is addressed to the question of how nocturnal partial sleep following TSD affects this relapse. Thirty endogenously depressed patients participated in the study. During the night after TSD, subjects were allowed sleep during one of three periods, i.e., unlimited sleep (11:00 p.m.-8:00 a.m.), early partial sleep (11:00 p.m.-3:00 a.m.), or late partial sleep (4:00 a.m.-8:00 a.m.). The hypothesis that partial sleep deprivation on the night following TSD prevents relapse has to be rejected. Relapse was inversely related to a drop in minimum rectal temperature during the night with unlimited or partial sleep, compared with minimum rectal temperature on the previous night.

Thyrotropin (TSH) and thyroid hormone concentrations during partial sleep deprivation in patients with major depressive disorder

Thyrotropin (TSH), thyroxine (T4), free T4, triiodothyronine (T3), and free T3 (fT3) concentrations were measured in 25 patients with major depressive disorder at 8 a.m. both before and after partial sleep deprivation (PSD) during the second half of the night. Significant increases in TSH and T3 levels and a corresponding trend in fT3 levels were seen. No convincing correlations occurred between changes in the secretion of any of the hormones and the antidepressant effect of PSD. However, this does not rule out the possibility that the two phenomena, which occur in depression at different anatomical levels with presumably different degrees of disturbance in the respective receptor systems, have common underlying neurochemical mechanisms. Comparison of the effect of the PSD on changes in hormone secretion and mood with the corresponding effects in a sample of depressed patients who underwent total sleep deprivation showed no significant differences between the effects of these two forms of sleep deprivation on either variable.

Therapeutic sleep deprivation in depressives, restricted to the two nocturnal hours between 3:00 and 5:00

1. In 33 patients with a depressive syndrome the effects of partial SD restricted to the 2 hours between 3:00 and 5:00 in the morning was compared to that of no SD (= undisturbed sleep, n = 17) and total SD (n = 16) in a balanced crossover design. 2. Partial SD had a moderate antidepressant effect which is, however, clearly inferior to that of total SD. 3. Reasons for the scarceness of the effect may be an inappropriate timing of this 2-hr SD period (which seems improbable), too short a duration of SD, or the resumption of sleep at 5 o'clock. 4. "Intermediate" SD in the form it was used here represents no therapeutic advantage as we had expected. Its moderate effects lend support to the hypothesis that sleep disturbance is a sign of (mostly insufficient) restorative or self-healing efforts of the depressive organism.

Geophysical variables and behavior: LVII. Seasonal affective disorder and phototherapy

Seasonal affective disorder, depressive symptoms that recur in fall and winter and abate in spring-summer, for many patients in the United States and Europe, have been alleviated by exposure to bright, full spectrum light for several hours daily (phototherapy). The characteristics of these patients, the procedures used, the theoretical explanations of the mechanisms, and the potential of phototherapy are reviewed.

Circadian rhythms in depression and recovery: evidence for blunted amplitude as the main chronobiological abnormality

Circadian rhythms of body temperature, plasma cortisol, norepinephrine (NE), thyroid stimulating hormone (TSH), and melatonin were compared in 16 endogenously depressed, 15 recovered (after 3 weeks of anti-depressant treatment), and 16 normal subjects. The depressed patients showed clear circadian rhythm abnormalities, consisting mainly in amplitude reduction. This amplitude reduction was significantly correlated with the patients' Hamilton depression scores. Normal circadian profiles were restored after recovery when amplitude, in particular, was increased. Features of the circadian rhythms observed in remission may be associated with antidepressant drug effects, whereas those observed in depression resemble the circadian rhythms observed in normal subjects living under conditions of temporal isolation and those of blind subjects. Our findings suggest that depression may be related both to a weakening of the coupling processes between internal pacemakers and to an abnormal sensitivity to environmental information.

Effects of chronic clonidine administration and withdrawal on free-running circadian activity rhythms

This study examined the effects of the alpha 2-adrenergic agonist clonidine on free-running circadian activity rhythms in rats, using a dosing regimen similar to one previously shown to induce behavioral depression in the swim test. In constant light, clonidine consistently shortened the free-running circadian period, reduced circadian amplitude, and reduced the overall level of locomotor activity. These effects were reversed after the termination of clonidine treatment. In constant darkness, clonidine reduced circadian amplitude, but both increases and decreases in free-running period and activity level were observed. Clonidine-induced changes in free-running period and activity level were systematically related to individual differences in baseline activity in both constant light and constant darkness. These results demonstrate that clonidine can alter both the rhythmicity and the level of spontaneous activity, and are consistent with the hypothesis that monoaminergic systems may mediate relationships between behavioral state and circadian rhythmicity.

REM sleep deprivation increases early morning pineal melatonin in castrated rats

Recently nighttime melatonin levels have been shown to be attenuated in depressive patients or patients with dementia of the Alzheimer type. On the other hand, depression can be transiently relieved by deprivation of rapid eye movement sleep. Since exogenous melatonin administration increases rapid eye movement sleep and slow wave sleep in the rat, could rapid eye movement sleep deprivation then inversely influence endogenous melatonin production? We found indices that in castrated Wistar rats 4 days of rapid eye movement sleep deprivation by the cuff pedestal method elevates the pineal content of melatonin by a factor of two at 1 to 2 h after light onset. Rapid eye movement sleep is thus suggested to influence pineal activity. This mechanism might be involved in the human depression-alleviating effect of rapid eye movement sleep deprivation.

Effect of different photoperiod exposure on [3H]imipramine binding and serotonin uptake in the rat brain

Seasonal rhythmicity in the occurrence of acute depressive episodes and the therapeutic efficacy of light exposure suggest the possible involvement of the pineal gland or other biological oscillators in the pathophysiology of depressive illness. We have performed studies to clarify whether different light/dark (LD) cycle schedules may induce changes in the biochemical targets of antidepressants in the rat CNS. In particular, we have investigated the effect of short- (LD 8:16) or long-day (LD 14:10) photoperiods on different biochemical parameters of serotonergic neurons. A significant increase in the density of [3H]imipramine ([3H]IMI) binding and in the Vmax of 5-[3H]hydroxytryptamine (5-[3H]HT) uptake was found in the hypothalamus of LD 8:16-with respect to LD 14:10-exposed rats, whereas no difference was found in the kinetic properties of postsynaptic 5-HT receptors and in 5-HT metabolism in the hypothalami and cerebral cortices of rats exposed to the two different photoperiods. A seasonal rhythm of [3H]IMI binding sites and 5-HT uptake seems to exist only in certain brain areas, such as the hypothalamus, because no differences were found in the cerebral cortex of LD 14:10- and LD 8:16-accustomed rats. [3H]IMI binding and 5-HT uptake were significantly increased in the hypothalamus of rats accustomed to a light/dark-inverted cycle (DL 10:14) and killed 6 h after the stopping of lighting in comparison to rats exposed to normal LD 14:10 cycles and killed 6 h after the beginning of lighting. Therefore, a circadian modification of the serotonergic presynaptic sites seems to be present and related to light/dark exposure. Because the existence of endogenous compounds able to modulate [3H]IMI binding and 5-HT uptake, other than 5-HT, has been postulated in the mammalian brain, the involvement of these substances in the periodic changes observed could be suggested.

Sleep architecture changes in depression: interesting finding or clinically useful

1. Since the late 1970's, considerable progress in the description and quantification of EEG sleep changes in depression has been made. A consistent finding in the sleep of depressed patients is a shortening of the time from sleep onset to the appearance of the first REM period (short REM latency) suggesting that this finding might be used as a clinical test to differentiate depressed from nondepressed patients. 2. Sleep architecture changes in depression are described and factors influencing REM sleep are identified. The stability of REM sleep abnormalities and the specificity of these changes for depression are discussed. Methodological issues, which have been identified as possible contaminants affecting the reliability of research findings, are described before the author concludes with a summary of current obstacles to using polysomnography in the clinical assessment of depressed patients.

Neuroendocrine mediated effects of electromagnetic-field exposure: possible role of the pineal gland

Reports from recent epidemiological studies have suggested a possible association between extremely low frequency (ELF; including 50- or 60-Hz) electric- and magnetic-field exposure, and increased risk of certain cancers, depression, and miscarriage. ELF field-induced pineal gland dysfunction is a possible etiological factor in these effects. Work in our laboratory and elsewhere has shown that ELF electromagnetic-field exposure can alter the normal circadian rhythm of melatonin synthesis and release in the pineal gland. Consequences of reduced or inappropriately timed melatonin release on the endocrine, neuronal, and immune systems are discussed. Laboratory data linking ELF field exposure to changes in pineal circadian rhythms in both animals and humans are reviewed. The authors suggest that the pineal gland, in addition to being a convenient locus for measuring dyschronogenic effects of ELF field exposure, may play a central role in biological response to these fields via alterations in the melatonin signal.

Entrainment of a free-running human with bright light?

The case of a 40-year-old sighted woman with free-running sleep-wake and melatonin rhythms is presented. The subject was studied for 102 days. During the pre-treatment period, both the sleep-wake and melatonin rhythms had a period of 25.1 hr, similar to the average period of humans living in temporal isolation. Treatment consisted of bright artificial light exposure (2500 lx Vita-Lite) for 2 hr each day upon awakening. Clock time of light exposure was held constant for 6 days and then slowly advanced until the subject was arising at her desired time of day. The subject continued the light treatment at home and was able to live on a 24-hr day for the 30-day follow-up study. While other factors may be operating in this situation, it is possible that the light treatment caused the stabilization of the free-running rhythms, advancement to a normal phase and entrainment to the 24-hr day. We suspect that the tendency to free-run was related to sleep onsets that were abnormally delayed relative to the circadian phase response curve for light. By scheduling a 2-hr pulse of bright light each morning, this tendency to delay would be counteracted by light-induced advances, resulting in normal entrainment.

[Lithium, manic depressive psychoses and biological rhythms]

Lithium is one of the rare substances capable of disturbing the body's “biological clock”. Clinical, biochemical and physiological observations allow us to view the Manic Depressive Illness pathogeny and the mechanism of lithium action in terms of biological rhythm modification.

Clinical and biochemical manifestations of depression. Relation to the neurobiology of stress (2)

Thousands of studies have been conducted of the functioning of the many neurotransmitter systems in order to explore the biologic basis of major depressive disorder. Instead of reviewing this literature exhaustively, we have attempted to propose a model that accommodates the clinical observation that chronic stress early in life in vulnerable persons predisposes them to major depression with contemporary observations of the potential consequences of repeated central nervous system exposure to effectors of the stress response. This model accords with current clinical judgment that major depression is best treated with a combination of psychopharmacologic agents and psychotherapy. Accordingly, whereas psychopharmacologic intervention may be required to resolve an active episode of major depression and to prevent recurrences, psychotherapy may be equally important to lessen the burden of stress imposed by intense inner conflict and counterproductive defenses.

Environmental and behavioral influences on affective illness

A behavioral factor, sleep, and a physical environmental factor, light, can trigger or terminate episodes of affective illness. The authors review the experimental evidence for these effects and discuss recent research on their biological mechanisms. In light of these findings the authors speculate that affective illness could partly be a disorder of systems that mediate the organism's adaptations to changes in the physical environment.

On the contribution of sleep wake physiology to the explanation and the treatment of depression

Physiological exploration has disclosed profound disturbances in the regulation of sleep in depression. The finding that depression can be relieved or intensified by manipulation of sleep has inspired the investigation of the possible pathogenetic significance of these dysregulations. Three hypotheses play a leading role in this context: the "phase-advance", the "S-deficiency" and the "acetylcholine-monoamine imbalance" hypothesis. They explain the therapeutic effects of a variety of sleep wake manipulations as consequences of the normalization of depressogenic sleep regulation disturbances. The issue discussed in this paper is whether these claims are valid. To what extent can the hypotheses explain the existing sleep physiological disturbance in depression as well as the results of therapeutic interventions in sleep? The empirical data provide firm evidence for the importance of particularly the timing of sleep in relation to the course of depression, both in respect to the spontaneous and the experimentally induced fluctuations of the clinical state. Without considerable extensions none of the hypotheses provide an adequate explanation of these facts.

Circadian oscillations of DNA synthesis in rat brain

The possibility that the synthesis of brain DNA undergoes a circadian fluctuation was examined in male adult Wistar rats, kept under natural lighting conditions or born and raised under artificial lighting conditions. Groups of rats were taken every 4 h during the 24 h, injected subcutaneously with [methyl-3H]thymidine and killed 4 h later. By cosinor analysis, the DNA specific activity of cerebral hemispheres and brainstem was found to show a significant 24 h rhythm with the peak at the beginning of the dark period (waking period). By contrast, in kidney, the peak of the circadian rhythm of DNA specific activity occurred during the light period (sleep period), in agreement with literature data. On the other hand, in 4-week-old rats, born and raised in artificial lighting conditions, brain DNA specific activity followed a 12 h rhythm, in agreement with the lack of a significant diurnal oscillation of the sleep--waking structure. It is concluded that brain DNA synthesis undergoes a circadian fluctuation in association with the circadian rhythm of waking.

Long-term effects of inescapable stress on daily running activity and antagonism by desipramine

The behavioral consequences of exposure to stressors such as inescapable shock are usually transitory if testing is conducted in an environment different from that in which the stressor was administered. The behaviors tested have generally been motivated by discrete stimuli in the environment (e.g., activity in reaction to shock) or have been part of homeostatic regulatory mechanisms (e.g., eating). Here we investigated the effects of inescapable shock on a behavior that is not so tightly tied to motivating and reinforcing conditions, daily activity in a familiar home cage/running wheel environment. Rats lived in the wheel environment for 44-85 days before treatment. Inescapable shock produced only a transient reduction of water intake and body weight, but daily running was depressed for 14-42 days (the maximum period studied) depending on the conditions. This long-term effect on activity occurred despite the fact that shock was administered in an environment very different from the animal's home running wheel environment. The activity reduction was reversed by desipramine in a dose dependent fashion. Indeed, the activity of inescapably shocked animals treated with the optimum dose of desipramine exceeded that of control animals undergoing neither stress nor drug treatment. The maximum effect of desipramine required 7 days of treatment. Desipramine did not affect the activity of control subjects.

The timing and duration of sleep in partial sleep deprivation therapy of depression

The antidepressant response to partial sleep deprivation early in the night (PSD-E) was compared with the response to partial sleep deprivation late in the night (PSD-L) in 16 drug-free depressed inpatients using a balanced order crossover design. PSD-L had a significantly greater antidepressant effect that PSD-E. The response to PSD-L was sustained and enhanced by a second night of treatment. Patients had significantly shorter sleep durations and reduced REM sleep on PSD-L that did not occur in the PSD-E situation. There was a significant negative correlation between response to PSD and sleep duration, and in particular, REM sleep duration, in the late sleep deprivation situation. Thus, the amount and timing of sleep appear to be factors in the response to PSD, but additional studies are needed to evaluate the relative importance of these parameters.

Chronic exposure to ELF fields may induce depression

Exposure to extremely-low-frequency (ELF) electric or magnetic fields has been postulated as a potentially contributing factor in depression. Epidemiologic studies have yielded positive correlations between magnetic- and/or electric-field strengths in local environments and the incidence of depression-related suicide. Chronic exposure to ELF electric or magnetic fields can disrupt normal circadian rhythms in rat pineal serotonin-N-acetyltransferase activity as well as in serotonin and melatonin concentrations. Such disruptions in the circadian rhythmicity of pineal melatonin secretion have been associated with certain depressive disorders in human beings. In the rat, ELF fields may interfere with tonic aspects of neuronal input to the pineal gland, giving rise to what may be termed "functional pinealectomy." If long-term exposure to ELF fields causes pineal dysfunction in human beings as it does in the rat, such dysfunction may contribute to the onset of depression or may exacerbate existing depressive disorders.

Delayed sleep phase syndrome in adolescents

The delayed sleep phase syndrome is characterized by difficulty in falling asleep at a socially acceptable time of night and an inability to be easily aroused in the morning. Most commonly encountered in adolescents, this condition can produce daytime sleepiness and poor school performance, and it can lead to behavioral problems. The clinical features of the syndrome are described in 22 adolescents. Nine subjects participated in a protocol of polysomnographic recordings to simulate habitual "weekday" and "weekend" sleep patterns. There was a significant increase in total sleep time (p less than 0.005) and REM sleep (p less than 0.001) during the "weekend" sleep period. A multiple sleep latency test was performed between the two nights to assess daytime sleep tendency. Daytime sleepiness was maximal in the morning, with a tendency for greater alertness as the day progressed. The reduced amount of REM sleep during the "weekdays" plus the tendency for sleepiness in the mornings may contribute to the behavioral and educational difficulties seen in these patients. Recognition of this syndrome enables a specific sleep schedule change to be made that effectively treats the problem.

Mood change following an acute delay of sleep

A phase advance of some circadian rhythms (e.g., body temperature and rapid eye movement [REM] sleep propensity) relative to the sleep-wake cycle is thought to be implicated in the pathophysiology and pathogenesis of some affective disorders. Since this phase disturbance can be induced in normal subjects by acutely delaying their sleep onset, it follows that the outcome of this experimental procedure should resemble the symptoms of depressive illness. This hypothesis was tested by imposing a 6-hour phase delay of sleep in 10 young male subjects. There were reliable changes in observers' ratings of mood and in some self-report measures. For the most part, the effect was modest, being largely confined to variations within normal limits. Two of the subjects, however, were noticeably depressed when interviewed after either the first or the second night of phase shift.