L-Theanine May Modestly Improve Subjective Sleep Quality
Key takeaway
L-theanine may help some people sleep subjectively better with a generally favorable safety profile in studied doses, but benefits and effect sizes vary and are not guaranteed.
- The clearest signal is better self-rated sleep for some users.
- Latency and efficiency may improve modestly in some trials.
| Claim | Scientific Observation | Impact Magnitude | ||
|---|---|---|---|---|
| Subjective sleep quality | May improve in trials/MAs | Modest / variable | ||
| Latency & efficiency | Mixed but often favorable | Small average effects | ||
| Exact SMD (−0.83) | Needs verified MA citation | Softened until linked | ||
| Safety absolute | Generally well tolerated | Not “zero side effects” |