Surprising
L-Theanine improved sleep efficiency in an ADHD supplement review — but it failed to move any other sleep parameter measured.
This is one of the first reviews to flag a sleep-specific effect for L-theanine in the context of ADHD, but the finding is narrow (only one sleep metric improved) and comes from a systematic review that didn't specify dose or sample size, so treat it as an early signal, not a settled benefit.
A systematic review of supplements for ADHD found that L-theanine helped people fall or stay asleep more efficiently, but it did not improve total sleep time, how long it took to fall asleep, or how rested they felt. The same review found stronger and broader benefits for other supplements like Bacopa monnieri, and the authors stress that supplements should only be used alongside, not instead of, standard treatments.
Where this fits in the evidence
This is among the first studies we've indexed on L-Theanine for Improved Sleep Efficiency — treat it as an early signal until more research accumulates.
The study
- Systematic Review
- 2025-04-28
- Nutrients
- PubMed: 40362791
- DOI: 10.3390/nu17091482
- Full study breakdown →
This is a plain-language summary of a research finding, not medical advice. Pillser surfaces research signals to help you decide what's worth investigating — always consult a qualified professional before changing what you take.