H. W. Agnew

SLEEP PATTERNS IN YOUNG ADULTS: AN EEG STUDY.

Abstract 1. 1. EEG sleep stages do not appear in any consistent temporal sequence from night to night in a given subject nor in a group of subjects. 2. 2. The typical young adult in our study spent an individually characteristics relative amount of time in each sleep stage each night. 3. 3. The length of stages was short, usually less than 10 min, with the exception of stage 1-REM which ranged up to 39 min in length. Our subjects characteristically changed stages fewer times on successive nights. The number of sleep stage changes differed among subjects. 4. 4. The stage change was usually smooth, moving from one stage to the next when sleep was deepening, but less smooth, often “jumping”.

Stage 4 Sleep: Influence of Time Course Variables

Age, length of prior wakefulness, length of time asleep, and a circadian influence all affect stage 4 sleep. The amount of stage 4 sleep decreases as subjects age increases and as time asleep increases. Longer periods of wakefulness before sleep result in greater amounts of stage 4 sleep in the first 3 hours of sleep. Sleep periods that begin at times other than the regular onset time tend to produce less stage 4 sleep; this decrease suggests a circadian effect.

Sleep Stage Characteristics of Long and Short Sleepers

The possibility of different sleep stage characteristics being associated with different sleep lengths was explored by comparing two groups of high school seniors, who characteristically slept 6� hours or less or who slept 8� hours or more, with an age-matched control group not selected on the basis of sleep length. All-night electroencephalography was used to examine the sleep stage characteristics of these groups. Compared with the unselected age-matched group, the short sleepers showed no significant diminution in their stage 4 (deep) or rapid eye movement (dream) sleep. The long sleepers were observed to obtain significantly more rapid eye movement sleep than did the other groups.

Characteristics of sleep patterns during late pregnancy and the postpartum periods

Abstract The present investigation provides an accurate description of the EEG sleep pattern characteristics of late pregnancy and early postpartum periods and compares this with age-matched controls. The over-all sleep pattern observed in gestation seemed similar in some respects to insomnia and was characterized by a longer sleep latency, frequent awakenings, shorter sleep time, and a marked reduction of deep sleep (Stage 4). In addition, immediately after delivery, there was a suppression of the dreaming (Stage 1-REM) sleep. By the second postpartum week, these profound sleep changes tended to normalize. Mechanisms of these findings and their possible relationship to postpartum emotional disturbances are discussed.

Sleep patterns in late middle age males: An EEG study

Abstract The EEG of sixteen 50–60 year old males was recorded and analyzed for the last 3 nights of sleep in the laboratory. The sleep of this group of subjects showed a marked reduction in the amount of EEG defined stage 4 sleep when compared with a group of younger subjects. In addition the group of older subjects showed an impressive distribution of stage 0 toward the last third of sleep. Four alternative hypotheses were examined in order to account for a decline in stage 4 sleep time by this age. None of these were sufficiently impelling to accept.

Sleep patterns in the young adult female: An EEG study

Abstract In this study of the sleep of young females additional support was found for the hypothesis that an individual spends a characteristic mount of time in each sleep stage. The length of stages was short, usually ten minutes. These stage changes were usually smooth, moving from one stage to the next when sleep was deepening, but less smooth during arousal from deeper levels. Stages IV and III showed their greatest amounts during the first third of the night and 1-REM during the ladt third. Comparisons between this group of young females and a group of males in the same age range revealed no significant differences for these EEG parameters of sleep.

Sleep during the early morning

The intrasleep EEG characteristics of Ss who returned to sleep in the early morning more closely resemble the sleep characteristics which occur late in a full nights sleep rather than the sleep which occurs at the onset of nocturnal sleep. It would appear that sleep does not simply “recycle” with sleep onset.

Effects on Performance of High and Low Energy-Expenditure during Sleep Deprivation

8 Ss were sleep deprived for 2 nights, using 2 different deprivation conditions. In the bed-rest condition Ss rested in bed while being sleep deprived. In the exercise condition Ss remained active and exercised for 15 min. on an exercise bicycle every other hour. Performance measures were obtained before, during, and after sleep deprivation. The two conditions did not differentially affect sleep during recovery nor did they have differential effects on performance during deprivation. From these results we infer that in operational settings it is unlikely that performance decrements during sleep deprivation can be offset by having personnel reduce their activity level.

Sleep Deprivation, Age, and Exhaustion Time in the Rat

Male rats were maintained on a constantly moving wheel in a study of prolonged sleep deprivation. The results obtained revealed a striking negative relationship between age and resistance to exhaustion.

Sleep latencies in human subjects: Age, prior wakefulness, and reliability

The latencies of sleep onset defined by EEG criteria were examined for seven age groups ranging from 21–31 months to 60–69 years. There was a decline in mean latencies with age except for the 60- to 69-year-old group. Forty percent of the latencies were less than 5 min in the 16- to 69-year age range. Latencies were positively related to prior wakefulness. Night-to-night latencies showed a low inter-S reliability.