The sleep supplement market is full of products backed by weak, inconsistent, or fabricated evidence. This is an evidence-only ranking — no marketing claims, no brand preferences, just what the clinical literature actually supports.
Key Takeaways
- Most proprietary blends contain each ingredient below the clinically effective threshold — the label is marketing, not a protocol
- Valerian root has a Cochrane Review showing insufficient evidence for sleep — yet remains one of the best-selling sleep supplements
- Glycine (3g, 30 min before bed) reduces core body temperature and improves next-day cognitive performance in RCTs — underrated
- CBD shows benefit at clinical doses (150–300mg) for anxiety-driven insomnia; largely unsupported at commercial doses (10–50mg)
- The supplement with the largest effect size for most people is magnesium — because most people are deficient, not because it is a powerful sedative
The Evidence-Based Supplement Stack
- Tier 1 — Start here: Magnesium glycinate (200–400mg elemental) + Glycine (3g) taken together 30–60 min before bed
- Add if stress or racing mind: L-Theanine 200mg with the above — reduces cognitive arousal without daytime drowsiness
- Add if chronic stress is confirmed: Ashwagandha KSM-66 (300–600mg daily) — effects emerge at 4–6 weeks, not overnight
- For circadian issues only: Melatonin 0.3–0.5mg timed correctly (see dedicated Melatonin Timing Guide)
- Correct deficiencies first: Test and address Vitamin D and Magnesium before layering additions — deficiency correction outperforms most supplements
- Avoid: Valerian root (weak evidence), high-dose melatonin (>1mg), proprietary blends with undisclosed individual quantities
How to Test Supplements With Your Wearable
Testing rule
Add one supplement at a time. Run it for 2–3 weeks before adding the next. You cannot identify which one moved the needle otherwise.
Glycine response
Lower overnight minimum HR + improved deep sleep % are the clearest glycine signals. Typically visible within 1–2 weeks in responders.
Ashwagandha response
HRV improvement over 4–6 weeks. Slow signal — do not judge within the first 2 weeks. Compare 30-day HRV before and after.
Non-response signal
No data movement + no subjective improvement after 4 weeks = eliminate it and try the next tier. Let the data decide.
Evidence Tier Ranking
| Supplement | Tier | Best Use Case | Dose |
|---|---|---|---|
| Magnesium Glycinate | ✓✓ Tier 1 | General sleep quality, deficiency correction | 200–400mg elemental |
| Glycine | ✓✓ Tier 1 | Sleep onset, core temp, next-day cognition | 3g, 30 min before bed |
| Melatonin (low dose) | ✓✓ Tier 1 | Jet lag, circadian phase shifting | 0.3–0.5mg, timed correctly |
| L-Theanine | ✓ Tier 2 | Stress-driven onset difficulty | 200mg before bed |
| Ashwagandha KSM-66 | ✓ Tier 2 | Chronic stress, elevated cortisol | 300–600mg daily, 4–6 wk onset |
| Valerian Root | ✗ Tier 4 | Not supported by current evidence | — |
| High-dose Melatonin (5–10mg) | ✗ Tier 4 | Counter-productive at this dose range | — |