Jet lag is caused by the disturbance of normal body rhythms as a result of flying across different time zones. Melatonin plays a part in controlling daily body rhythms.
A recent review found 10 randomised controlled trials comparing melatonin with placebo in long distance travellers. Eight of the 10 trials found a clear reduction in jet lag when melatonin had been taken.
The review concludes that 2-5mg melatonin taken at bedtime after arrival is effective and may be worth repeating for the next two to four days, together with several behavioural measures to adjust the body clock.
In the United States, Thailand, and Singapore, melatonin is freely sold as a "dietary supplement" in health food stores and pharmacies, although no official standards of purity exist. In Europe, Australia, and many other countries, melatonin is defined as a medicine and requires a licence, but no licensed preparation is marketed; only the internet offers a grey or black market.
It seems that many people and organisations, including governments and armed forces, would benefit from the use of melatonin to reduce jet lag, say the authors. If use of the drug is in the public interest, then public funds should be used to get it properly tested and licensed. A finance initiative is urgently needed to solve the problem and might best begin with a cost benefit assessment, they conclude.