Robin Bjorheim

Abstract

One of every 5th person in Europe works night shift. Although research has shown negative effects of night shift on cognitive measures, work related accidents and health, little is known of the daytime sleep. Light on night shift induces effects on alertness and the regulation of sleep and wakefulness. The aim of our study was to characterize the daytime sleep when working night shift in two different wavelengths of light (blue-enriched 455 nm and red-enriched light 615 nm). Polysomnographic recording of the sleep were performed for one nighttime and the following sleep after simulated night shifts (23:00-07:00). Night shift consisted of computerized tasks in the laboratory in ceiling LED-luminaires. Day-time sleep showed a reduced total sleep time compared to night sleep. The time in N3 was preserved, at the expense of time in stage N1, N2 and REM sleep. There were no significant differences between day sleep blue and day sleep red. The sleep pressure, measured by slow wave activity (SWA), declined during sleep for both day-sleep and night-sleep. Significant higher SWA were found for day-sleep versus night-sleep. The dissipation of the sleep pressure, measured by and slow wave energy (SWE) were seen for both night and day-sleep as well as significant differences of day-sleep compared to night-sleep. These results contribute to the understanding of daytime sleep after working night shifts.

This master’s project was part of the project:
Consequences of night shift simulation on waking performance, sleep, circadian rhythmicity and brain function. 

Supervisors

Main supervisor   Janne Grønli
Co-supervisor  Torhild Pedersen