Some effects of jet-lag and their alleviation by melatonin

Abstract

Seventeen healthy volunteers (10 women and 7 men, aged 29-68) were flown from London to San Francisco between 20 November 1985 and 25 January 1986 and remained there for 14 days prior to flight home. Subjects took melatonin (N = 8, 5 women, 3 men) or placebo in a double-blind design, at 18.00h local time for three days before the return flight and at bedtime (22.00-24.00h) in Great Britain for four days. For three days before departure and on days 1-7,14,15, 21 and 22 after their return subjects collected 6-hourly sequential urine samples and kept a daily sleep log. They recorded mood and oral temperature 2 hourly and performed logical reasoning and letter cancellation tests 4 hourly from 08.00h (or wake up time) to 24.00h (or bedtime) whichever was the earlier. Urine was also collected for 48 h prior to departure from the U.S.A‥ On day 7 after their return subjects rated ‘jet lag’ (10 cm visual analogue scale—VAS) from 0 (insignificant) to 100 (very bad). Melatonin significantly improved ‘jet lag’ (p= 0.009). Comparisons by ANOVA between jet-lagged placebo subjects (N = 7) and melatonin (N = 8) showed decreased sleep latency with melatonin (p= 0.0397) which correlated positively with jet lag ratings, p< 0.001. Sleep quality was significantly improved in the melatonin group and correlated negatively with jet-lag ratings (pp= 0.0216 and p= 0.0299 respectively, absolute acrophase shifts). Cortisol rhythms indicated adaptation to U.S.A. time in 14 days. These data suggest that MT can alleviate jet-lag after Eastward flight over eight time zones. Presumably its affects are primarily on sleep latency, quality, and directly or indirectly on some hormonal rhythms.