Citation

Thessing VC, Anch AM, Muehlbach MJ, Schweitzer PK, Walsh JK. Sleep 1994; 17(2): 140-145.

Affiliation

Sleep Disorders and Research Center, Deaconess Medical Center, St. Louis, MO 63139.

Copyright

(Copyright © 1994, American Academy of Sleep Medicine, Publisher Associated Professional Sleep Societies)

DOI

unavailable

PMID

8036368

Abstract

The effect of two durations of bright light upon sleepiness and performance during typical night shift hours was assessed. Thirty normal, healthy young adults participated in a 2-night protocol. On the 1st night subjects were exposed to bright or dim light beginning at 2400 hours, under one of the following three conditions: bright light for 4 hours, dim light for 2 hours followed by bright light for 2 hours or dim light for 4 hours. Following light exposure, subjects remained awake until 0800 hours in a dimly lit room and slept in the laboratory between 0800 and 1600 hours, during which time sleep was estimated with actigraphy. Throughout the 2nd night, the multiple sleep latency test (MSLT), simulated assembly line task (SALT) performance, and subjective sleepiness were recorded. The single, 4-hour exposure to bright light was found to significantly increase MSLT scores and improve SALT performance during the early morning hours on the night following bright-light exposure. No significant effects were noted with a 2-hour exposure. The most likely explanation for these findings is a phase delay in the circadian rhythm of sleepiness-alertness.

Language: en