Abstract: In the last decade there has been an upsurge in the research focusing on the interplay between the human circadian timing system and behavioral patterns in health and illness. Of particular interest in this area of inquiry is the overlay of what has been termed chronotype. What this refers to is the propensity of biological rhythms to express themselves in certain patterns of behavior. Commonly, these patterns have received names such as owl (evening chronotype) or lark (morning chronotype). Many people are neither a strong morning nor evening chronotype. If illness represents a change in the way a person's body functions within a given environment, then it is reasonable to believe that an "owl's" symptom presentation may vary significantly from the patterns of a "lark" who becomes ill. Recognizing that psychiatric nurses at both the generalist and the advanced practice levels have a strong interest in patterns of behavior, it stands to reason that using a lens that incorporates notions of the body's clock becomes essential. The interplay between the body's timing system and the thousands of other psychobiological rhythmic functions occurring everyday and within every human being is referred to as chronobiology. This article provides a primer for psychiatric nurses on issues of chronobiology related to morningness and eveningness rhythm propensity.

Abstract: : This limited review suggests that some traditional factors like, personality and circadian amplitude seem to have little to do with tolerance of shift work. Neither does gender, at least not if social responsibility is controlled for. Age on the other hand seems of more interest and also diurnal type, but the two seem closely related. However, the major determinants of shift work tolerance probably have more to do with states or rather ways of coping with irregular work hours. Thus, the way an individual organizes his behavior to promote sleep may be of importance, as may be the need for sleep. This may be related to commitment to night work, avoiding light after night work, etc. One should probably give priority to teaching sleep/wake optimization, rather than trying to find individuals with particular traits. One gets the feeling that the highly tolerant single night shift worker would be older, have a low need for sleep, have a high sleep quality, be in good physical shape, and plan sleep strategically (using naps). If several night shifts occur in sequence, younger individuals may have an advantage.

Abstract: : The changes in performance that arise in shiftworkers and after transmeridian flights can be attributed, at least in part, to the reduction in both the quality and quantity of sleep which occurs as a result of disruption of the normal pattern of sleep and wakefulness. Sleep disturbance associated with shiftwork is well documented.

Abstract: The purpose of this study was to investigate the effects of shift system, age, and chronotype on the sleep habits, sleepiness and catnaps of shift workers during night work. We administrated a Morningness-Eveningness Questionnaire and Life Habits Inventory to 561 male shift workers of three different shift systems in Korea. The mean scores on the Morningness-Eveningness Questionnaire clearly shifted toward the Morning type from the young to old groups. The waking and bedtimes during the day and evening shift were earlier for the older than for the younger groups, and these times were earlier across the Evening, Intermediate, to Morning type as well. Sleep length during the day shift was longer from the young to old, and it was shorter from the Evening, Intermediate, to Morning type. In the weekly rotation full-day 3-team 3-shift system and continuous full-day 3-team 3-shift system (which had earlier starting times for day shift) the sleep length of the younger workers was short. For the aged workers, slee...

Abstract: Seasonal variations in sleep characteristics and their association with changes in mood were examined in 91 American men and women also who spent the 1991 austral winter at three different research stations in Antarctica. Measures of total hours of sleep over a 24-hr period, duration of longest (i.e.,"nighttime") sleep event, number of sleep events, time of sleep onset, and quality of sleep remained unchanged over the course of the austral winter (March through October). However, exposure to total darkness based on station latitude was significantly associated with total hours of sleep, duration of are longest sleep event, time of sleep onset, and quality of sleep. Reported vigor the previous month was a significant independent predictor of changes in all five sleep measures; previous month's measures of all six POMS subscales were significant independent predictors of sleep quality. Sleep characteristics were significant independent predictors of vigor and confusion the following month; total sleep, longest sleep event, sleep onset and sleep quality were significant independent predictors of tension-anxiety and depression. Changes in mood during the austral winter are preceded by changes in sleep characteristics, but prolonged exposure to the photoperiodicity characteristic of the high latitudes appears to be associated with improved sleep. In turn, mood changes appear to affect certain sleep characteristics, especially sleep quality.

Abstract: SUMMARY The night sleep of 48 healthy drug-free infants, aged 1–54 weeks, was recorded and analysed in order to show how cycles contribute to sleep episode organization and how the balance among different sleep states (i.e. quiet sleep, paradoxical sleep and ambiguous sleep) within cycles changes as a function of age. A greater proportion of time spent in cycles (TCT) on total sleep time (TST), as a result of the lengthening of sleep cycles, was found in older infants, whereas sleep out of cycles decreases with age. The internal structure of the sleep cycles also changes with age, because of the increase in the proportion of quiet sleep (QS), the appearance of slow wave sleep (SWS) from the 21st week onwards, and the decrease in ambiguous sleep. The proportion of paradoxical sleep (PS), however, remains stable throughout the first year of age. The improvement of sleep organization across the first year of life is paralleled by an internal restructuring of the cycle, involving mainly changes in QS. We may speculate that both changes, one involving the lengthening of cycle and the other involving the increase in QS component, contribute to the improvement of biological and psychological sleep functions during development.

Abstract: The circadian pacemaker and sleep homeostasis play pivotal roles in vigilance state control. It has been hypothesized that age-related changes in the human circadian pacemaker, as well as sleep hom...