Field trial of timed bright light exposure for jet lag among airline cabin crew

Abstract

Objectives. Commercial airlines' flight crew members on transmeridian long-haul flights are constantly exposed to rapid changes in external time. Following rapid changes in circadian rhythm may lead to several symptoms known as jet lag. Our aim was to alleviate jet-lag symptoms by timed exposure to bright light (natural sunlight if present, otherwise artificial bright light).Study Design. Observational field trial with bright light against jet lag.Methods. Information on the effects of bright lights on health was delivered through corporate level wellness programs. Volunteer study subjects were cabin crew members on long-haul flights. Subjects filled in a 16-Item Columbia Jet Lag Scale (maximum score 64) before the flight (expected symptoms based on previous flights), on the third day at the destination and again on the third day after returning home. Changes in scores were compared relative to the timed exposure to bright light, and to flights eastwards or westwards, and in summer or winter.Results. Out of 75 subjects, 15 returned the questionnaires for a total of 28 flights. The mean estimated effect of bright light was a decrease of 5.3 points on the symptom scale. The difference was not significant (SE = 3.4, df = 11, t = -1.6, p = 0.15). The flight had no influence on the estimate.Conclusions. The results do not give support to the hypothesis that timed exposure to bright light would alleviate jet lag symptoms, although the small sample size was a problem. More field studies are needed to establish the feasibility of bright light for reducing jet lag.