The importance of timing in melatonin administration in a blind man.

An 18-year-old blind man suffered from chronic sleep disturbances associated with daytime fatigue and excessive daytime somnolence. After two unsuccessful treatment regimens with 5 mg and 10 mg melatonin administered at bedtime (2200-2230), a third regimen of 5 mg melatonin administered at 2000 for 3 weeks resulted in a successful resolution of his sleep disturbances. We suggest that the efficacy of melatonin in ameliorating sleep disturbances because of alterations in circadian rhythmicity may be dependent on the time of administration.