The 5 Best Sleep Supplements, Honestly Compared
Short on time?
For general sleep quality: magnesium glycinate, 200–400 mg before bed — gentle, well-studied, and the best value. For stress-driven trouble: ashwagandha. For a racing mind: L-theanine. For jet lag only: low-dose melatonin (0.5–1 mg, not 10). The reasoning and full comparison are below.
Most "best sleep supplement" lists are copy-paste marketing. This one is different: we only include supplements with multiple human trials behind them, we tell you what the trials actually measured, and we name one clear starting pick instead of hedging with five "winners."
Quick comparison
| Supplement | Best for | Evidence strength | Typical dose |
|---|---|---|---|
| 1. Magnesium glycinate | Overall sleep quality; most people | Moderate | 200–400 mg |
| 2. Glycine | Falling asleep faster | Moderate (small trials) | 3 g |
| 3. L-theanine | Racing mind at bedtime | Moderate | 100–200 mg |
| 4. Melatonin | Jet lag, shifted schedules | Strong (for timing issues) | 0.5–1 mg |
| 5. Ashwagandha | Stress-driven sleep trouble | Moderate | 300–600 mg extract |
The top pick: magnesium glycinate
If we had to pick one supplement for general sleep quality, it's magnesium glycinate. Magnesium plays a role in regulating the nervous system's "quiet down" signals, and the glycinate form is gentle on the stomach (unlike citrate, which is better known as a laxative). Trials on magnesium and sleep show modest but consistent improvements in sleep quality — modest is honest; anyone promising more is selling you something.
Magnesium Glycinate (via iHerb)
Well-absorbed, gentle form. Pick a third-party tested brand — we link the category so you can compare prices and reviews yourself.
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What does Reddit say?
We analyzed 1,673 Reddit threads across five sleep communities and ranked all twelve supplements by user-reported outcomes — glycine scored 97% positive, and the most-hyped supplement ranked last. See the Reddit ranking → · Compare any two supplements →
Also excellent
Glycine (3 g before bed) helped participants fall asleep faster and feel more rested in small Japanese trials. L-theanine is the pick if your problem is a racing mind rather than physical restlessness. Melatonin is genuinely strong for jet lag and shift work — it shifts sleep timing, it doesn't knock you out; most people take 5–10x more than the effective dose. Ashwagandha earns its place when stress is the root cause — see our full ashwagandha deep-dive.
How we evaluate
- Human trials only. Rat studies and petri dishes don't count.
- Multiple studies. One encouraging trial is a lead, not a conclusion.
- No disease claims. Supplements support sleep; they don't treat insomnia disorder. If you have chronic sleep problems, see a doctor.
- Safety first. We flag interactions (ashwagandha and thyroid medication, melatonin and blood thinners, and so on).
Bottom line
Start with the basics — consistent sleep schedule, dark room, no late caffeine — then, if you want a supplement, magnesium glycinate is the most sensible first try. Give any supplement 2–4 weeks before judging it.
CortiSync — KSM-66 Ashwagandha Complex
300mg KSM-66 per serving — the extract behind the cortisol trials — plus 11 other clinically-validated ingredients. Not for pregnancy or thyroid meds without a doctor's OK.
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