Dark goggles and bright light improve circadian rhythm adaptation to night-shift work

We compared the contributions of bright light during the night shift and dark goggles during daylight for phase shifting the circadian rhythm of temperature to realign with a 12-hour shift of sleep. After 10 baseline days there were 8 night-work/day-sleep days. Temperature was continuously recorded...

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Bibliographic Details
Published in:Sleep (New York, N.Y.) N.Y.), 1994-09, Vol.17 (6), p.535-543
Main Authors: EASTMAN, C. I, STEWART, K. T, MAHONEY, M. P, LIWEN LIU, FOGG, L. F
Format: Article
Language:English
Subjects:
Adaptation, Physiological
Adult
Affect - physiology
Applied physiology
Biological and medical sciences
Body Temperature - physiology
Circadian Rhythm - physiology
Ergonomics. Work place. Occupational physiology
Eye Protective Devices
Female
Human physiology applied to population studies and life conditions. Human ecophysiology
Humans
Light
Male
Medical sciences
Sleep - physiology
Space life sciences
Surveys and Questionnaires
Work Schedule Tolerance
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Summary:We compared the contributions of bright light during the night shift and dark goggles during daylight for phase shifting the circadian rhythm of temperature to realign with a 12-hour shift of sleep. After 10 baseline days there were 8 night-work/day-sleep days. Temperature was continuously recorded from 50 subjects. There were four groups in a 2 x 2 design: light (bright, dim), goggles (yes, no). Subjects were exposed to bright light (about 5,000 lux) for 6 hours on the first 2 night shifts. Dim light was < 500 lux. Both bright light and goggles were significant factors for producing circadian rhythm phase shifts. The combination of bright light plus goggles was the most effective, whereas the combination of dim light and no goggles was the least effective. The temperature rhythm either phase advanced or phase delayed when it aligned with daytime sleep. However, when subjects did not have goggles only phase advances occurred. Goggles were necessary for producing phase delays. The most likely explanation is that daylight during the travel-home window after a night shift inhibits phase-delay shifts, and goggles can prevent this inhibition. Larger temperature-rhythm phase shifts were associated with better subjective daytime sleep, less subjective fatigue and better mood.
ISSN:0161-8105
1550-9109
DOI:10.1093/sleep/17.6.535