The impact of tryptophan supplementation on sleep quality: a systematic review, meta-analysis, and meta-regression.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of clinical trials
PubMed 33942088 · doi:10.1093/nutrit/nuab027
What was done
Researchers searched PubMed, Medline, CINAHL, and Cochrane databases for studies evaluating the effect of L-tryptophan supplementation on sleep quality. From 18 identified articles, data from 4 studies were pooled using random-effects meta-analysis and meta-regression to evaluate overall efficacy and compare daily doses of less than 1 g versus 1 g or more.
What was found
Tryptophan supplementation significantly reduced wake after sleep onset (-81.03 min/g, P = 0.017; SMD, -1.08 min [95% CI, -1.89 to -0.28]). Doses of 1 g or greater resulted in shorter wake after sleep onset compared to doses under 1 g (28.91 min vs 56.55 min, P = 0.001). Tryptophan supplementation did not significantly affect other measured sleep components.
Why it matters
This review quantifies the specific impact of L-tryptophan on sleep maintenance, indicating that doses of at least 1 g daily may help reduce nighttime waking.
Limits
Only 4 of the 18 identified studies contained data suitable for the quantitative meta-analysis. Total participant count, baseline sleep disorder status, participant demographics, and specific adverse effects were not reported in the abstract. The supplement showed no demonstrated effect on sleep parameters other than wake after sleep onset.
Cited by
- supports Tryptophan is an amino acid in the serotonin synthesis pathway that induces sleep.