Use of melatonin in recovery from jet-lag following an eastward flight across 10 time-zones

Subjective, physiological and physical performance variables are affected f ollowing travel across multiple time-zones (jet-lag). The objective of the study was to examine the effects of oral melatonin in alleviating jet-lag b y investigating its effects on subjects who had flown from London to Easter n Australia, 10 time-zones to the east. Melatonin (5 mg day(-1)) or placebo capsules were administered to 14 experimental (13 males and 1 female) and 17 control subjects (15 males and 2 females), respectively, in a double-bli nd study; the time of administration was in accord with the current consens us for maximizing its hypnotic effect. Grip strength and intra-aural temper ature were measured on alternate days after arrival at the destination, at four different times of day (between the times 07:00-08:00 h, 12:00-13:00 h , 16:00-17:00 h and 19:00-20:00 h local time). In addition, for the first 6 -7 days after arrival in Australia, subjective ratings of jet-lag on a 0-10 visual analogue scale and responses to a Jet-lag Questionnaire (incorporat ing items for tiredness, sleep, meal satisfaction and ability to concentrat e) were recorded at the above times and also on retiring (at about midnight ). Subjects continued normally with their work schedules between the data c ollection times. Subjects with complete data (13 melatonin and 13 placebo s ubjects), in comparison with published data, showed partial adjustment of t he diurnal rhythm in intra-aural temperature after 6 days. A time-of-day ef fect was evident in both right and left grip strength during adjustment to Australian time; there was no difference between the group taking melatonin and that using the placebo. Right and left grip strength profiles on day 6 were adjusted either by advancing or delaying the profiles, independent of whether subjects were taking melatonin or placebo tablets. Subjects report ed disturbances with most measures in the Jet-lag Questionnaire but, wherea s poorer concentration and some negative effects upon sleep had disappeared after 3-5 days, ratings of jet-lag and tiredness had not returned to `zero ' (or normal values), respectively, by the sixth day of the study. Subjects taking melatonin showed no significant differences from the placebo group in perceived irritability, concentration, meal satisfaction, ease in gettin g to sleep and staying asleep, frequency of bowel motion and consistency of the faeces. These results suggest that, in subjects who, after arrival, fo llowed a busy schedule which resulted in frequent and erratic exposure to d aylight, melatonin had no benefit in alleviating jet-lag or the components of jet-lag, and it did not influence the process of phase adjustment.