Missed antenatal depression among high risk women: a secondary analysis.

Psychiatrically high-risk women were recruited for a postpartum depression prevention trial. Participants were screened at entry (20-26 weeks gestation) by a psychiatrist prior to receiving randomized treatment. Of the 31 patients who did not complete the study, 10 (33%) were dropped because of diagnosed depression. Only two women developed major depression in the postpartum period. Our data suggests, among high-risk women, obstetric care providers may be overlooking up to one fifth of women with current major depression.

Melatonin and human chronobiology.

With the development of accurate and sensitive assays for measuring melatonin in plasma and saliva, it has been possible to advance our understanding of human chronobiology. In particular, the dim light melatonin onset (DLMO) is expected to have an increasingly important role in the diagnosis of circadian phase disorders and their treatment with appropriately timed bright light exposure and/or low-dose melatonin administration. The phase angle difference (PAD) between DLMO and mid-sleep can be used as a marker for internal circadian alignment and may also be used to differentiate individuals who are phase advanced from those who are phase delayed (a long interval indicates the former and a short interval indicates the latter). To provide a corrective phase delay, light exposure should be scheduled in the evening and melatonin should be administered in the morning. To provide a corrective phase advance, light exposure should be scheduled in the morning and melatonin should be administered in the afternoon/evening. The study of patients with seasonal affective disorder (SAD), as well as individuals who are totally blind, has resulted in several findings of interest to basic scientists, as well as psychiatrists and sleep specialists.

Capturing the circadian rhythms of free-running blind people with 0.5 mg melatonin.

We have recently shown that six of seven totally blind people (who had free-running circadian rhythms with periods longer than 24 h) could be entrained (synchronized) to a nightly dose of 10 mg melatonin. After treatment discontinuation and re-entrainment to the 10 mg dose, we further found in three of these subjects that the dose could be gradually reduced to 0.5 mg without loss of effect. The question then arose: can a de novo (starting) dose of 0.5 mg initially capture free-running rhythms? Following withdrawal of the stepped-down 0.5 mg dose and consequent release into a free-run, the same three individuals were given 0.5 mg of melatonin de novo. All entrained within a few weeks.

Pretreatment circadian period in free-running blind people may predict the phase angle of entrainment to melatonin.

To date, we have entrained (synchronized) eight totally blind people with free-running circadian rhythms to a nightly dose of 10 mg of melatonin. Each person entrained at a different phase angle of entrainment (PAE), which is the interval in hours between the time of the melatonin dose and the time of the endogenous melatonin onset. When the PAE was plotted against the pretreatment free-running (i.e. slightly different than 24.0 h) circadian period (tau), the fitted regression line revealed a significant correlation, which is consistent with previous findings on light entrainment of rest-activity rhythms in free-running rodents [Pittendrigh and Daan, J. Comp. Physiol., 106 (1976) 291-331].

Melatonin in plant organs.

The indoleamine melatonin, a well-known animal chemical, has been identified in extracts from several plant species. The function of melatonin in plants is unknown. Two major functions of melatonin in animals are dark signaling and antioxidant protection. Fruit ripening was used as a model physiological process that involves changes in the oxidative status of an organ. Tomato fruits at various stages of ripeness were sampled. Morning glory (Pharbitis nil Choisy, cv. Violet) and tomato (Lycopersicon esculentum Mill., cv. T5 and Castlemart) organs were collected throughout a light/dark cycle to determine whether melatonin levels increased during the night. No consistent evidence was found that melatonin increased significantly in organs of these plants during the night, as it does in many animals. The melatonin content of the fruits generally increased during ripening up to the mature ripe stage and thereafter as the fruit became over ripe.

Effects of aging on the intrinsic circadian period of totally blind humans.

Age-related changes in the intrinsic circadian period (tau) have been hypothesized to account for sleep symptoms in the elderly such as early morning awakening. The authors sought to determine whether the aging process produced quantifiable differences in the tau of totally blind men who had free-running circadian rhythms. The melatonin onset was used as the indicator of circadian phase. Melatonin rhythms had been characterized about a decade previously when the participants were 38 +/- 6 (SD) years old. Both previous and current assessments of tau were derived from at least 3 serial measurements of the 24-h melatonin profile from which the melatonin onset was determined. All 6 participants exhibited a longer tau in the 2nd assessment (mean increase +/- SD of 0.13 +/- 0.08 h; p < 0.01). Four participants exhibited differences in tau with nonoverlapping 95% confidence intervals. The results do not support the commonly held view that tau shortens during human aging. On the contrary, tau appears to slightly, but significantly, lengthen during at least 1 decade in midlife.

Entrainment of free-running circadian rhythms by melatonin in blind people.

BACKGROUND: Most totally blind people have circadian rhythms that are "free-running" (i.e., that are not synchronized to environmental time cues and that oscillate on a cycle slightly longer than 24 hours). This condition causes recurrent insomnia and daytime sleepiness when the rhythms drift out of phase with the normal 24-hour cycle. We investigated whether a daily dose of melatonin could entrain their circadian rhythms to a normal 24-hour cycle. METHODS: We performed a crossover study involving seven totally blind subjects who had free-running circadian rhythms. The subjects were given 10 mg of melatonin or placebo daily, one hour before their preferred bedtime, for three to nine weeks. They were then given the other treatment. The timing of the production of endogenous melatonin was measured as a marker of the circadian time (phase), and sleep was monitored by polysomnography. RESULTS: At base line, the subjects had free-running circadian rhythms with distinct and predictable cycles averaging 24.5 hours (range, 24.2 to 24.9). These rhythms were unaffected by the administration of placebo. In six of the seven subjects the rhythm was entrained to a 24.0-hour cycle during melatonin treatment (P<0.001). After entrainment, the subjects spent less time awake after the initial onset of sleep (P=0.05) and the efficiency of sleep was higher (P=0.06). Three subjects subsequently participated in a trial in which a 10-mg dose of melatonin was given daily until entrainment was achieved. The dose was then reduced to 0.5 mg per day over a period of three months; the entrainment persisted, even at the lowest dose. CONCLUSIONS: Administration of melatonin can entrain circadian rhythms in most blind people who have free-running rhythms.

Melatonin suppression by light in euthymic bipolar and unipolar patients.

BACKGROUND: Previous studies have suggested that bipolar patients are supersensitive to light suppression of melatonin and that this may be a trait marker for genetic vulnerability. The present study was an attempt to replicate and extend this observation. Propranolol hydrochloride effects were compared with light effects because of the documented influence of beta-adrenergic receptors on melatonin production. Nighttime levels of corticotropin and cortisol were also examined as potential trait vulnerability markers. METHODS: Melatonin levels in euthymic bipolar patients (n= 29) were tested before and after 500-lux light was administered between 2 and 4 AM and on a separate night in the dark. Results were compared with those of a group of patients with unipolar depression (n= 24) and with those of a group of non-psychiatrically ill control subjects (n= 50). Lithium effects and propranolol effects were tested in subgroups. RESULTS: No group differences were seen in light suppression among bipolar patients, unipolar patients, and controls; an analysis of the whole group did not reveal differences in propranolol effect, differences in corticotropin or cortisol levels, or evidence for a lithium effect. However, patients with bipolar I affective disorder showed the following: (1) significantly lower melatonin levels on the light night, at baseline and following light exposure; and (2) a later peak time for melatonin on the dark night. CONCLUSIONS: The general hypothesis of increased light sensitivity in bipolar patients was not supported. However, melatonin secretion abnormalities were confirmed in the subgroup with bipolar I disorder. Further assessments of circadian rhythm disruption as a vulnerability marker in bipolar illness are indicated.

Transcription factor dynamics and neuroendocrine signalling in the mouse pineal gland: a comparative analysis of melatonin-deficient C57BL mice and melatonin-proficient C3H mice.

In rodents, the nocturnal rise and fall of arylalkylamine N-acetyltransferase (AANAT) activity controls the rhythmic synthesis of melatonin, the hormone of the pineal gland. This rhythm involves the transcriptional regulation of the AANAT by two norepinephrine (NE)-inducible transcription factors, e.g. the activator pCREB (phosphorylated Ca2+/cAMP-response element binding protein) and the inhibitor ICER (inducible cAMP early repressor). Most inbred mouse strains do not produce melatonin under standard laboratory light/dark conditions. As melatonin-deficient mice are often the founders for transgenic animals used for chronobiological experimentations, molecular components of neuroendocrine signalling in the pineal gland as an integral part of clock entrainment mechanisms have to be deciphered. We therefore compared calcium signalling, transcriptional events and melatonin synthesis in the melatonin-deficient C57BL mouse and the melatonin-proficient C3H mouse. Pineal glands and primary pinealocytes were cultured and stimulated with NE or were collected at various times of the light/dark (LD) cycle. Changes in intracellular calcium concentrations, the phosphorylation of CREB, and ICER protein levels follow similar dynamics in the pineal glands of both mouse strains. pCREB levels are high during the early night and ICER protein shows elevated levels during the late night. In the C57BL pineal gland, a low but significant increase in melatonin synthesis could be observed upon NE stimulation, and, notably, also when animals were exposed to long nights. We conclude that the commonly used C57BL mouse is not completely melatonin-deficient and that this melatonin-deficiency does not affect molecular details involved in regulating transcriptional events of melatonin synthesis.

Does our DNA determine when we sleep?

The discovery and study of three kindreds with advanced sleep phase disorder shed light on how we can inherit tendencies to be early morning or late night kinds of people (pages 1062-1065).

Jet lag: clinical features, validation of a new syndrome-specific scale, and lack of response to melatonin in a randomized, double-blind trial.

OBJECTIVE: The goals of this study were to validate a new rating scale for measuring severity of jet lag and to compare the efficacy of contrasting melatonin regimens to alleviate jet lag. METHOD: This was a randomized, double-blind trial of placebo and three alternative regimens of melatonin (5.0 mg at bedtime, 0.5 mg at bedtime, and 0.5 mg taken on a shifting schedule) for jet lag. The subjects were 257 Norwegian physicians who had visited New York for 5 days. Jet lag ratings were made on the day of travel from New York back to Oslo (6 hours eastward) and for the next 6 days in Norway. The main outcome measures were scale and item scores from a new, syndrome-specific instrument, the Columbia Jet Lag Scale, that identifies prominent daytime symptoms of jet lag distress. RESULTS: There was a marked increase in total jet lag score in all four treatment groups on the first day at home, followed by progressive improvement over the next 5 days. However, there were no significant group differences or group-by-time interactions. In addition, there was no group effect for sleep onset, time of awakening, hours slept, or hours napping. Ratings on a summary jet lag item were highly correlated with total jet lag scores (from a low of r = 0.54 on the day of travel to a high of r = 0.80 on day 3). The internal consistency of the total jet lag score was high on each day of the study. CONCLUSIONS: The use of melatonin for preventing jet lag needs further study.

The endogenous melatonin profile as a marker for circadian phase position.

Several circadian rhythms have been used to assess the phase of the endogenous circadian pacemaker (ECP). However, when more than one marker rhythm is measured, results do not always agree. Questions then inevitably arise. Are there multiple oscillators? Are some markers more reliable than others? Masking is a problem for all marker rhythms. Masking of melatonin is minimized by sampling under dim light. The dim-light melatonin onset (DLMO) is particularly convenient since it can usually be obtained before sleep. However, assessing the DLMO in low melatonin producers may be problematic, particularly with the commonly used operationally defined threshold of 10 pg/ml. This study evaluates various circadian phase markers provided by the plasma melatonin profile in 14 individuals, several of whom are low melatonin producers. The amount (amplitude) of melatonin production appears to influence the phase of many points on the melatonin profile. Accordingly, when low producers are in a data set, we now prefer a lower DLMO threshold than the one previously recommended (10 pg/ml). Indeed, there are some low producers who never exceed this threshold at any time. Radioimmunoassays are now available that have the requisite sensitivity and specificity to support the use of a lower threshold. Nevertheless, the dim-light melatonin offset (DLMOff), even when operationally defined at thresholds less than 10 pg/ml, appears to be confounded by amplitude in this study; in such cases, it may be preferable to use the melatonin synthesis offset (SynOff) because it is not confounded by amplitude and because, theoretically, it is temporally closer to the endogenous mechanism signaling the offset of production. The question of whether the termination mechanism of melatonin synthesis is related to an interval timer or to a second oscillator loosely coupled to the onset oscillator is probably best answered using the SynOff rather than the DLMOff. It is hoped that these findings will make a useful contribution to the debate on the best ways to use points on the melatonin profile to assess circadian phase position in humans.

The dim light melatonin onset, melatonin assays and biological rhythm research in humans.

The most useful marker for human circadian phase position is the dim light melatonin onset (DLMO). This is optimally obtained by sampling blood or saliva in the evening at intervals of 30 min or less. Ambient light intensity should not exceed 30-50 lx. For many years, the DLMO was determined mainly with the 'gold standard' GCMS technique for measuring melatonin in human plasma. However, new and improved RIAs now provide the requisite sensitivity and accuracy (specificity) for detecting the time that low daytime levels begin to increase in the evening: the lower the operational threshold for the DLMO, the more reliable it is as a phase marker.

Morning vs evening light treatment of patients with winter depression.

BACKGROUND: According to the phase-shift hypothesis for winter depression, morning light (which causes a circadian phase advance) should be more antidepressant than evening light (which causes a delay). Although no studies have shown evening light to be more antidepressant than morning light, investigations have shown either no difference or morning light to be superior. The present study assesses these light-exposure schedules in both crossover and parallel-group comparisons. METHODS: Fifty-one patients and 49 matched controls were studied for 6 weeks. After a prebaseline assessment and a light/dark and sleep/wake adaptation baseline week, subjects were exposed to bright light at either 6 to 8 AM or 7 to 9 PM for 2 weeks. After a week of withdrawal from light treatment, they were crossed over to the other light schedule. Dim-light melatonin onsets were obtained 7 times during the study to assess circadian phase position. RESULTS: Morning light phase-advanced the dim-light melatonin onset and was more antidepressant than evening light, which phase-delayed it. These findings were statistically significant for both crossover and parallel-group comparisons. Dim-light melatonin onsets were generally delayed in the patients compared with the controls. CONCLUSIONS: These results should help establish the importance of circadian (morning or evening) time of light exposure in the treatment of winter depression. We recommend that bright-light exposure be scheduled immediately on awakening in the treatment of most patients with seasonal affective disorder.

Evaluation of the Actillume wrist actigraphy monitor in the detection of sleeping and waking.

This study evaluated the Actillume instrument and the modified Action 3 sleep-wake scoring algorithm, in which the scoring factor (P) was set at 0.10, 0.14, 0.20, 0.30, 0.40 and 0.50. Fifteen subjects, each of whom underwent polysomnography with simultaneous wrist actigraphy four times, yielded a total of 60 sleep studies. The sleep data from each subject were divided into four groups. In the high sleep efficiency index groups of the calibration and validation samples, the accuracy of the algorithm significantly differed within six P-values and was highest at P=0.14. In the low sleep efficiency index groups of both samples, however, there were no significant differences in the accuracy. Thus, these results indicate that P=0.14 should be most appropriate for this actigraph and algorithm.

Use of melatonin for sleep and circadian rhythm disorders.

Although not licensed as a drug, melatonin is widely sold as a nutritional supplement in the USA for its purported sleep-promoting and antiageing properties. In this article, we provide some guidelines for its use in sleep disorders medicine. In brief, melatonin appears to promote sleep by producing corrective circadian phase shifts, thereby improving the alignment of the endogenous sleep propensity rhythm with the desired sleep schedule. Melatonin may also have a direct soporific effect, especially when administered during the day. We suggest that the direct soporific action results from the release of accumulated sleep drive by melatonin's attenuation of the circadian alerting signal. Melatonin has not been proven safe by the usual clinical trial criteria, but to date no catastrophes have been related to its use. Also, there is little information about the safety and efficacy of chronic administration.

The role of melatonin and circadian phase in age-related sleep-maintenance insomnia: assessment in a clinical trial of melatonin replacement.

The present investigation used a placebo-controlled, double-blind, crossover design to assess the sleep-promoting effect of three melatonin replacement delivery strategies in a group of patients with age-related sleep-maintenance insomnia. Subjects alternated between treatment and "washout" conditions in 2-week trials. The specific treatment strategies for a high physiological dose (0.5 mg) of melatonin were: (1) EARLY: An immediate-release dose taken 30 minutes before bedtime; (2) CONTINUOUS: A controlled-release dose taken 30 minutes before bedtime; (3) LATE: An immediate-release dose taken 4 hours after bedtime. The EARLY and LATE treatments yielded significant and unambiguous reductions in core body temperature. All three melatonin treatments shortened latencies to persistent sleep, demonstrating that high physiological doses of melatonin can promote sleep in this population. Despite this effect on sleep latency, however, melatonin was not effective in sustaining sleep. No treatment improved total sleep time, sleep efficiency, or wake after sleep onset. Likewise, melatonin did not improve subjective self-reports of nighttime sleep and daytime alertness. Correlational analyses comparing sleep in the placebo condition with melatonin production revealed that melatonin levels were not correlated with sleep. Furthermore, low melatonin producers were not preferentially responsive to melatonin replacement. Total sleep time and sleep efficiency were correlated with the timing of the endogenous melatonin rhythm, and particularly with the phase-relationship between habitual bedtime and the phase of the circadian timing system.