Non-rapid eye movement sleep

About: Non-rapid eye movement sleep is a research topic. Over the lifetime, 8661 publications have been published within this topic receiving 389465 citations. The topic is also known as: NREM.

An endogenous circadian rhythm in sleep inertia results in greatest cognitive impairment upon awakening during the biological night

Abstract: Sleep inertia is the impaired cognitive performance immediately upon awakening, which decays over tens of minutes. This phenomenon has relevance to people who need to make important decisions soon after awakening, such as on-call emergency workers. Such awakenings can occur at varied times of day or night, so the objective of the study was to determine whether or not the magnitude of sleep inertia varies according to the phase of the endogenous circadian cycle. Twelve adults (mean, 24 years; 7 men) with no medical disorders other than mild asthma were studied. Following 2 baseline days and nights, subjects underwent a forced desynchrony protocol composed of seven 28-h sleep/wake cycles, while maintaining a sleep/wakefulness ratio of 1:2 throughout. Subjects were awakened by a standardized auditory stimulus 3 times each sleep period for sleep inertia assessments. The magnitude of sleep inertia was quantified as the change in cognitive performance (number of correct additions in a 2-min serial addition test) across the first 20 min of wakefulness. Circadian phase was estimated from core body temperature (fitted temperature minimum assigned 0°). Data were segregated according to: (1) circadian phase (60° bins); (2) sleep stage; and (3) 3rd of the night after which awakenings occurred (i.e., tertiary 1, 2, or 3). To control for any effect of sleep stage, the circadian rhythm of sleep inertia was initially assessed following awakenings from Stage 2 (62% of awakening occurred from this stage; n = 110). This revealed a significant circadian rhythm in the sleep inertia of cognitive performance (p = 0.007), which was 3.6 times larger during the biological night (circadian bin 300°, ~2300–0300 h in these subjects) than during the biological day (bin 180°, ~1500–1900 h). The circadian rhythm in sleep inertia was still present when awakenings from all sleep stages were included (p = 0.004), and this rhythm could not be explained by changes in underlying sleep drive prior to awakening (changes in sleep efficiency across circadian phase or across the tertiaries), or by the proportion of the varied sleep stages prior to awakenings. This robust endogenous circadian rhythm in sleep inertia may have important implications for people who need to be alert soon after awakening.

Electroencephalographic sleep of adolescents with major depression and normal controls.

Abstract: • Forty-nine, mostly outpatient (86%), nonbipolar adolescents, aged Tanner stage III to 18 years, with a current diagnosis of major depressive disorder and 40 adolescents without current presence or history of psychiatric disorder were studied polysomnographically for three consecutive nights. Sleep latency was significantly longer in the depressive groups. The nonendogenous depressive patients exhibited significantly more awake time and lower sleep efficiency during the sleep period. No significant group differences were found for first rapid eye movement (REM) period latency, REM density, or any other REM sleep measures. Age correlated significantly with REM latency and delta sleep time, especially among depressive patients. No significant correlations between sleep measures and severity of illness were found. It appears that the classic REM sleep findings associated with the adult depressive syndrome are not present among depressive adolescents, indicating a later ontogeny for these abnormalities.

Sleep as a mediator of the stress-immune relationship.

Abstract: OBJECTIVE To evaluate the role of sleep in the relationship of intrusive thoughts/avoidance behaviors to natural killer cell (NKC) number and function. METHOD Twenty-nine individuals seeking treatment for bereavement-related depression were studied in the sleep laboratory. Background and clinical variables, including the Impact of Event Scale (IES) and the Hamilton Rating Scale for Depression (HRSD), were administered during the week preceding a 3-night sleep study. Blood samples were collected upon awakening after the second or third night of sleep. RESULTS Greater frequency of intrusive thoughts and avoidance behaviors was associated with more time spent awake during the first non-rapid eye movement period (NREM-1) and lower NKC number (p values < .01). Greater time spent awake during NREM-1 was associated with lower NKC numbers (p < .05). Regression analyses revealed that the significant relationship between symptoms of intrusion/avoidance and NKC number was no longer significant when time spent awake during NREM-1 was entered into the regression equation. Time spent awake during NREM-1 accounted for 12% of the variance in NKC number (p < .05), whereas intrusion/avoidance accounted for 7% of the variance in NKC number (NS). CONCLUSIONS These results suggest that EEG-assessed sleep may be a significant correlate of the stress-immune relationship.