Elliot D. Weitzman

Human prolactin - 24-hour pattern with increased release during sleep.

Human prolactin was measured in plasma by radioimmunoassay at 20 minute intervals for a 24-hour period in each of six normal adults, whose sleep-wake cycles were monitored polygraphically. A marked diurnal variation in plasma concentrations was demonstrated, with highest values during sleep; periods of episodic release occurred throughout the 24 hours.

Chronobiology of aging: Temperature, sleep-wake rhythms and entrainment

Studies were carried out on a group of six young (ages 23-30) and six older (ages 53-70) normal men who lived under conditions of temporal, but not social isolation, from three to eight weeks. During entrained and non-entrained (free-running) conditions, comparative measurements were made of sleep-wake cycles, sleep stages and rectal temperature rhythms for these two age groups. Results demonstrated a reduction in the period and amplitude of the body temperature rhythms during free-running in the older group. Sleep efficiency, total sleep time, REM sleep latency, REM episode length, percent REM in the last 2 hours of sleep, the length and frequency of arousals during sleep, and the terminal wake latency were all age related and dependent on entrainment. The period of the sleep-wake cycle, terminal awakenings from REM and percent REM in the first 3 hours of sleep were not age related but were dependent on entrainment. Sleep stages as percents of total sleep time were found to be age related but independent of entrainment, while sleep latency, mid-REM to mid-REM cycle length and the ratio of sleep to total time were neither age related nor dependent on entrainment. In addition, individual chronobiological differences were prominent in the older group. Changes of period and of the phase relationship of sleep-wake and temperature rhythms occurred in several subjects during the non-entrained condition.

Auditory evoked responses during different stages of sleep in man

Responses to auditory stimuli can be recorded from the scalp of man in all stages of sleep. At the vertex, the mean peak latency of the first positive deflection (P1) occurs at 50 msec after stimulation; N1, at 100 msec; P2, at 175 msec; N2, at 325 msec; and P3 at 800 msec. The amplitude and latency of the components of longer latency (N2 and P3) increase during stages 2 through 4 sleep. The amplitude of the summed auditory evoked responses during the REM stage is considerably smaller than in the other stages and generally is of similar configuration to that of the awake state. Our results support the concept that the auditory evoked response during sleep represents summed K complexes.

ENTRAINMENT OF HUMAN ORCADIAN RHYTHMS BY LIGHT‐DARK CYCLES: A REASSESSMENT

Abstract— Man is the only eukaryotic organism in which it has been reported that the circadian system cannot be entrained to a 24‐h period by a simple light‐dark (LD) cycle. In this paper, we reexamine the evidence for that claim and demonstrate that there were some fundamental flaws in the experimental design of the previous studies on which this conclusion was based. We report new studies in which we tested the efficacy of LD cycles in entraining the circadian rhythms of human subjects living in isolation from environmental time cues. We found that the cyclic alternation of light and dark, when applied to human subjects in a comparable way to experiments in other species, was an effective entraining agent. Our results and a critical review of the literature indicate that a LD cycle alone can be an effective environmental synchronizer of the human circadian timing system. Other factors, such as the knowledge of time of day, social contacts, the feeding schedule, and the imposed rest‐activity schedule may contribute to stable entrainment, although their relative strengths as synchronizers have yet to be determined.

Obstructive sleep apnea and death associated with surgical correction of velopharyngeal incompetence

We have observed three children who developed obstructive sleep apnea immediately following construction of pharyngeal flaps designed to improve the speech of these patients with velopharyngeal incompetence. Postoperatively the patients were noted to have repeated episodes during sleep of strong respiratory efforts without airflow. Sleep apnea can be debilitating and lethal, and should be looked for following surgery of the upper airway. Respiratory depressants should be avoided. Airway intubation, revision of the surgery, or tracheostomy may be necessary.

Sleep Patterns of the Monkey and Brain Serotonin Concentration: Effect of p-Chlorophenylalanine

The amount of time that monkeys (Macaca mulatta) slept was reduced after they were given p-chlorophenylalanine, a selective depletor of serotonin in animal tissues. The time spent in the rapid eye movement stage of sleep was unchanged, but the time in other sleep stages decreased. Seven regions of the brain had a 31 to 46 percent decrease in serotonin content; the concentration of cerebellar serotonin increased by 44 percent.

The relationship of sleep and sleep stages to neuroendocrine secretion and biological rhythms in man.

Publisher Summary This chapter reviews the major new observations made regarding the temporal organization of the 24-hour pattern of hypothalamic-pituitary function in regard to sleepwaking function. It discusses the recent application of these results to certain clinical disorders. All the pituitary hormones studied with the technique of frequent plasma sampling have been found to be secreted in an episodic manner throughout the 24-hour day. These hormones have important temporal secretory pattern relationships with the sleepwaking 24-hour cycle. In addition, the sleep stage cyclic pattern during nocturnal sleep is closely related to the timing of several pituitary hormones indicating state control by the central nervous system (CNS) over the timing and amount of secretion under normal physiological conditions. Each system appears to have its own temporal organization and response to manipulations of the sleepwaking cycle, and no single principle or mechanism can be invoked to explain these differing patterns. The concept that a homesotatic steady state or basal level is present for any extended time period of the 24-hour day is clearly not the case. The data suggest that a major mechanism of control takes place by CNS 24-hour temporal programs that initiate secretion independent of existing plasma concentrations under normal stable conditions.

theoretical and Technical Problems in the Measurement of Nocturnal Penile Tumescence for the Differential Diagnosis of Impotence1

&NA; Theoretical and technical problems in using Nocturnal Penile Tumescence (NPT) measurements for the differential diagnosis of impotence are discussed and possible solutions are offered: 1) The basic assumption that NPT measurements can distinguish psychogenic from organic impotence has never been demonstrated in patients shown to be psychogenically and organically impotent independent of the NPT measurements themselves. Studies attempting to do this are necessary to determine definitively the limits of the clinical applicability of this important diagnostic tool. 2) Evidence is presented showing that though a direct observation of one of the patients fullest erections is required for an adequate NPT evaluation, this is not always done. The danger of misdiagnosis if this step is omitted is illustrated with a case report. 3) Disagreements in the literature about NPT criteria for diagnosing psychogenic impotence are discussed and criteria are suggested that are based on demonstrating the intactness of the physiological mechanisms required for erection rather than on values recorded in normal subjects.

Meal patterns in “free-running” humans☆

Abstract The meal patterns of men who were initiating meals for extended periods in the absence of time cues were examined. A significant, positive correlation was found between the sizes (in kcals) of mixed and varied meals and the lengths of postprandial intervals. This quantitative relationship between meal size and meal timing is similar to patterns reported for freely feeding rats. If postprandial correlations reflect a short term mechanism for energy regulation then when humans schedule their meals due to social or time considerations they may negate this contribution to the regulation of their energy intake.

Patterns of Spontaneous Cortisol and Growth Hormone Secretion in Rhesus Monkeys During the Sleep-Waking Cycle

Plasma concentrations of cortisol (F) and growthhormone were determined in samples obtained sequentially at 15 min intervals for 12 h night and 12 h day sessions in juvenile male monkeys (6–9.5 lb.) i