Abstract: The purpose of this study was to determine, in a large sample of adults of all ages (17-80 years), the effect of morningness/eveningness on sleep/wake schedules, sleep needs, sleep hygiene and subjective daytime somnolence. A total of 617 subjects (219 subjects per chronotype group) matched for age, sex and employment status, completed an abridged morningness/eveningness questionnaire, a questionnaire on sleep habits and the quality of sleep, and the Epworth Sleepiness Scale. Eveningness was associated with a greater need for sleep, less time in bed during the week compared to ideal sleep needs, more time in bed at the weekend, a later bedtime and waking-up time especially at the weekend, more irregular sleep/wake habits and greater caffeine consumption. These subjects built up a sleep debt during the week and extended their duration of sleep at the weekend. They did not, however, rate themselves more sleepy than other types, despite the fact that our results showed a clear link between subjectively evaluated daytime somnolence and sleep debt. Why they were less affected by sleep deprivation is not clear. This raises the question of individual susceptibility to the modification of sleep parameters.

Abstract: We investigated the relationship between sleep timing and the timing of the circadian rhythm of plasma melatonin secretion in a group of healthy young and older subjects without sleep complaints. The timing of sleep and the phase of the circadian melatonin rhythm were earlier in the older subjects. The relationship between the plasma melatonin rhythm and the timing of sleep was such that the older subjects were sleeping and waking earlier relative to their nightly melatonin secretory episode. Consequently, the older subjects were waking at a time when they had higher relative melatonin levels, in contrast with younger subjects, whose melatonin levels were relatively lower by wake time. Our findings indicate that aging is associated not only with an advance of sleep timing and the timing of circadian rhythms but also with a change in the internal phase relationship between the sleep-wake cycle and the output of the circadian pacemaker. In healthy older subjects, the relative timing of the melatonin rhythm with respect to sleep may not play a causal role in sleep disruption.

Abstract: Background: Travelling across multiple time zones disrupts normal circadian rhythms and induces “jet lag”. Possible effects of this on training and performance in athletes were concerns before the Sydney Olympic Games. Objective: To identify some determinants of jet lag and its symptoms. Methods: A mixture of athletes, their coaches, and academics attending a conference (n = 85) was studied during their flights from the United Kingdom to Australia (two flights with a one hour stopover in Singapore), and for the first six days in Australia. Subjects differed in age, sex, chronotype, flexibility of sleeping habits, feelings of languor, fitness, time of arrival in Australia, and whether or not they had previous experience of travel to Australia. These variables and whether the body clock adjusted to new local time by phase advance or delay were tested as predictors for jet lag and some of its symptoms by stepwise multiple regression analyses. Results: The amount of sleep in the first flight was significantly greater in those who had left the United Kingdom in the evening than the morning (medians of 5.5 hours and 1.5 hours respectively; p = 0.0002, Mann-Whitney), whereas there was no significant difference on the second flight (2.5 hours v 2.8 hours; p = 0.72). Only the severity of jet lag and assessments of sleep and fatigue were commonly predicted significantly (p Conclusions: These results indicate the importance of an appropriate choice of itinerary and lifestyle for reducing the negative effects of jet lag in athletes and others who wish to perform optimally in the new time zone.

Abstract: The majority of winter-type seasonal affective disorder (SAD) patients complain of hypersomnia and daytime drowsiness. As human sleep is regulated by the interaction of circadian, ultradian and homeostatic processes, sleep disturbances may be caused by either one of these factors. The present study focuses on homeostatic and ultradian aspects of sleep regulation in SAD. Sleep was recorded polysomnographically in seven SAD patients and matched controls subjected to a 120-h forced desynchrony protocol. In time isolation, subjects were exposed to six 20-h days, each comprising a 6.5-h period for sleep. Patients participated while being depressed, while remitted after light therapy and in summer. Controls were studied in winter and in summer. In each condition, the data of each subject were averaged across all recordings. Thus, the influence of the effects of the circadian pacemaker on sleep was excluded mathematically. The comparison of patients with controls and with themselves in the various conditions revealed no abnormalities in homeostatic parameters: sleep stage variables, relative power spectra and time courses of power in various frequency bands across the first three non-rapid eye movement-rapid eye movement (NREM-REM) cycles showed no differences. The data suggest that homeostatic processes are not involved in the disturbance of sleep in SAD.

Abstract: This report describes complex psychophysiological studies of nocturnal sleep in healthy humans in normal concentrations and after emotional tension. A series of contemporary methods was used: questionnaires, psychological tests, motor tests, and polysomnography with heart rate recording. These experiments showed that psychoemotional tension induced changes mainly in the structure of the first sleep cycle, decreasing the proportion of the second stage of slow sleep in total nocturnal sleep, led to a redistribution of delta sleep, increasing delta sleep in the second half of nocturnal sleep, and suppressed the mechanisms underlying the organization of the phases of rapid sleep. Psychoemotional tension affected human cerebrovisceral functions, for example inducing increases in the frequency and variability of the heart rhythm during nocturnal sleep. The nature of these changes in sleep structure and autonomic responses depended on the personality characteristics of the individual person. Thus, the individual approach to the question of psychoemotional stress in sleep disturbances is, we believe, the most appropriate.

Abstract: This review summarizes current knowledge of sleep disorders with a chronobiological basis, including: delayed sleep phase syndrome, advanced sleep phase syndrome, non24 h sleep-wake syndrome and irregular sleep-wake pattern disorder. These circadian rhythm sleep disorders are characterized by a misalignment between the timing of the sleep period with respect to the day-night cycle and as a consequence of patients attempting to maintain 'normal' social hours, reduced sleep quality. In addition to the specific circadian rhythm sleep disorders, this review will also examine current drug (e.g., hypnotics and melatonin) and nondrug (e.g., bright light therapy and chronotherapy) treatments, the overlap with psychophysiological insomnia and future directions.

Abstract: We performed a cross-sectional study with 342 medical students (age range, 18-35 years) to identify, among a group of sleep disturbances, those which are related to minor psychiatric disorders in this population. The instruments employed for data collection were the self-reporting questionnaire (SRQ-20), the morningness/eveningness questionnaire, the Epworth sleepiness scale, and a general questionnaire regarding demographic characteristics, use of drugs, history of psychopathology, usual fall-asleep time, usual wake-up time, amount of sleep, arousal during the night, and insomnia. We used a logistic regression model to determine independent factors associated with minor psychiatry disorders. Daytime sleepiness [odds ratio (OR), 2.12; 95% CI, 1.21-3.71], arousal [OR, 4.54; 95% CI, 1.97-10.47], insomnia [OR 2.45; 95% CI, 1.32-4.56], and sleeping less than 7 hours per night [OR, 2.02; 95% CI, 1.11-3.67] were associated with minor psychiatric disorders. This group of variables determined a cumulative risk ratio of 5.47 [95% CI, 2.87-10.41] for the main outcome.