BMJ  2006;332:550 (4 March), doi:10.1136/bmj.332.7540.550-a

Letter

Does melatonin improve sleep?

Muddles with melatonin

EDITOR—Buscemi et al assert that there is no evidence base for exogenous melatonin for secondary sleep disorder.¹

Lewy et al have shown that low doses of melatonin (0.5 mg) reset circadian rhythm but not high doses (2 mg).² The prolonged half life of melatonin and the sensitivity of the circadian rhythm to its presence mean that in trying to achieve phase advancement or phase delay melatonin has a limited window of opportunity. Too low a dose and no effect, too high and the chronobiological effects are lost and only the direct somnolent action is experienced.

Until very recently there have been no commercially available preparations of the correct dose, substantially hindering research. As melatonin is of most use where there is circadian rhythm dysregulation the correct dose must be used at the right time. It would be a shame if a potentially useful treatment for a limited range of disorders was discarded because of excess expectations and premature disappointment.

London NW6 6BX jan.wise{at}nhs.net

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Competing interests: MEJW uses melatonin and bright light to reduce recovery time from intercontinental jet lag (personal use only).

References

1. Buscemi N, Vandermeer B, Hooton N, Pandya R, Tjosvold L, Hartling L, et al. Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction: meta-analysis. BMJ 2006;332: 385-93. (18 February.)[Abstract/Free Full Text]
2. Lewy AJ, Emens JS, Sack RL, Hasler BP, Bernert RA. Low, but not high doses of melatonin entrained a free running blind person with a long circadian rhythm. Chronobiol Int 2002;19: 649-58.[CrossRef][ISI][Medline]

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Related Article

Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction: meta-analysis

Nina Buscemi, Ben Vandermeer, Nicola Hooton, Rena Pandya, Lisa Tjosvold, Lisa Hartling, Sunita Vohra, Terry P Klassen, and Glen Baker
BMJ 2006 332: 385-393. [Abstract] [Full Text] [PDF]