Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake

J Nerv Ment Dis. 1979 Aug;167(8):497-9.


Previous results have demonstrated sleep-inducing effects of L-tryptophan in doses of 1 to 15 g at bedtime. The present laboratory study extends the dose-response curve downward, comparing doses of 1/4 g, 1/2 g, and 1 g of L-tryptophan with placebo, in 15 mild insomniacs (subjects who reported sleep latencies of over 30 minutes). One gram of L-tryptophan significantly reduced sleep latency: the lower doses produced a trend in the same direction. Stage IV sleep was significantly increased by 1/4 g of L-tryptophan. These results at low doses have interesting implications since the normal dietary intake of L-tryptophan is 1/2 g to 2 g per day.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial

MeSH terms

  • Adult
  • Dose-Response Relationship, Drug
  • Humans
  • Male
  • Reaction Time / drug effects
  • Sleep / drug effects*
  • Sleep Initiation and Maintenance Disorders / drug therapy*
  • Sleep Stages / drug effects
  • Tryptophan / therapeutic use*


  • Tryptophan