Tryptophan for the treatment of excessive daytime sleepiness in Prader-Willi syndrome.

An 8-year old girl with Prader-Willi Syndrome presenting with excessive daytime sleepiness improved following treatment with tryptophan; possibly by consolidation of her fragmented sleep. Improvement was recorded on a follow-up sleep study, one year after initiating treatment with tryptophan. We conclude that tryptophan may be an useful medication for excessive sleepiness in children with Prader-Willi Syndrome.