Sleep on the Night Shift: 24‐Hour EEG Monitoring of Spontaneous Sleep/Wake Behavior

Abstract

The present study sought to objectively describe the spontaneous sleep/wakefulness pattern of shift workers during a 24-hour period. Portable Medilog tape-recorders were used for ambulatory EEG monitoring of 25 male papermill workers (25-55 years) during days with night and afternoon work. The results showed that sleep after night work was two hours shorter than after afternoon work. The sleep reduction affected mainly Stage 2 and REM sleep while slow wave sleep was unchanged. In connection with night work 28% of the workers took a nap in the afternoon. These naps contained a large proportion of slow wave sleep and were, apparently, caused by the sleep deficit after the short main sleep period. The EEG recordings also revealed that 20% of the participants had sleep episodes during night work. These naps were as long as the afternoon naps, were experienced as "dozing offs" rather than naps, occurred at the time of the trough of the circadian wakefulness rhythm, and were concomitant with extreme subjective sleepiness and low rated work load. It was concluded that not only the sleep of shift workers was disturbed, but also the wakefulness--to the extent that sleepiness during night work sometimes reached a level where reasonable wakefulness could not be maintained. The latter observation is probably of special importance in work situations demanding a great responsibility for human lives or for great economic values.

Spectral analysis of sleep electroencephalography in rotating three-shift work.

“…The lack of increased total amounts of SWS and SWE in night-shift sleep was expected from prior studies of shift workers (1)(2)(3)(4)(5)(6)(7)(8) . Admittedly, at first thought, one might expect increased slow-wave levels because of the prior sleep loss involved and its expected effects on SWS or SWE (10,21,23).…”

“…Mean and standard error (SE) per non-REM-REM sleep cycle for sleep parameters in connection with afternoon, morning , and night workshifts. a (SWE = slow-wave energy , SWA = slow-wave activity, SWS = slow-wave sleep , REM = rapid-eye- previous studies (1)(2)(3)(4)(5)(6)(7)(8). In other words, sleep after the night shift was reduced by more than 2 h, the loss affecting stage 2 and REM sleepmainly and SWS marginally.…”

“…The subjects participated in the earlier study by Torsvall et al (7), but the present recordings were carried out two years later. They belonged to the same work unit and received a modest economic compensation.…”

Organizational stressors and police performance

“…Research has also found negative associations between rotating schedules and employee productivity, safety and accident-proneness (Johnson et. al, 1981;Regestein and Monk, 1991), reduced total sleep and poorer sleep quality (Torsvall, et. al., 1989).…”

Sleep strategies of 12-hour shift nurses with emphasis on night sleep episodes

“…In contrast, descriptions of real sleep episodes during nightwork outside any specific experiment and without any formal authorization are scarce (10).…”