Light visor treatment for jet lag after westward travel across six time zones.

Oct 26, 2002Aviation, space, and environmental medicine

Light visor treatment for jet lag after traveling west across six time zones

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Abstract

Bright light treatment resulted in a 2.59 hour phase delay in circadian timing compared to a 1.58 hour delay with dim light following a westward flight.

Bright light exposure may enhance the adjustment of the body's internal clock after traveling across time zones.
No significant improvements in sleep efficiency, subjective sleep quality, or daytime functioning were observed between the two light groups.
Faster reaction times were noted in the dim light group, although this was not linked to changes in circadian phase or prior sleep.
The overall effects of bright light on jet lag symptoms were modest and did not translate into better performance or mood.

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INTRODUCTION: The aim of this field study was to evaluate the efficacy of a light treatment for jet lag, using a head-mounted light visor, following a westward flight across six time zones.

METHODS: There were 20 subjects who were exposed to bright white light (3000 lux) or dim red light (10 lux) for 3 h on the first two evenings after a flight from Zurich to New York. Salivary dim light melatonin onset (DLMO), assessed 2 d before and 2 d after the flight, provided a measure of circadian phase. Sleep was recorded by actigraphy, while post-flight performance testing and subjective scales provided additional indices of jet lag severity.

RESULTS: The DLMO measurements showed a larger phase delay in the bright light than in the dim light group (2.59 h vs. 1.58 h, p < 0.02). There was no overall difference in sleep efficiency (SE) between the two groups, but a significant Group x Night interaction reflected a small increase across the first two post-flight nights in the bright light group, and a small decrease in the dim light group. Reaction time on one of two performance tests was consistently faster in the dim light group, but was unrelated to circadian phase or to prior sleep. There were no major group differences in subjective sleep quality, daytime sleepiness, jet lag severity, or mood.

DISCUSSION: This is the first full-scale study to show that bright light treatment can accelerate circadian reentrainment following transmeridian travel. However, the effect on reentrainment rate was modest, and was not accompanied by any improvement in sleep, performance, or subjective assessments of jet lag symptoms.

Light visor treatment for jet lag after westward travel across six time zones.

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