Sleep supplements rated by the evidence
Most sleep supplements rest on small studies. Some are cheap and safe enough to try, a few have real risks, and none replaces a consistent schedule. Each guide states the dose used in studies, the strength of the evidence and what to check before you take it.
Guides
- L-Theanine for Sleep: What the Research Shows, How Much to Take and How It Works With CaffeineL-theanine may modestly improve how well you think you sleep, how fast you fall asleep and how you feel the next day. A 2025 meta-analysis of 19 randomized trials found small to moderate benefits on self-reported sleep, and trials of L-theanine alone mostly used 200 to 450 mg per day. It calms rather than sedates, and evidence for objective sleep changes is limited.6 min read, 8 sources
- Glycine for Sleep: What the Trials Found, the Right Dose and Whether Collagen Before Bed HelpsSmall Japanese trials found that 3 g of glycine before bed improved how rested people felt in the morning, shortened the time to fall asleep and reduced next-day fatigue after short sleep. The evidence is limited to a few small studies, several from researchers at an amino acid manufacturer, so glycine is a cheap and low-risk experiment rather than a proven sleep aid.7 min read, 6 sources