Melatonin for Cognitive Function
Melatonin is not a reliable way to improve cognition. A few small meta-analyses hint at a modest benefit in Alzheimer's and mild cognitive impairment, but the signal is weak, contested, and not endorsed by any regulator or medical society for this use.
Why this grade7-layer evidence engine
The grade is Weak (Tier C, disputed) because the evidence points in different directions depending on who is treated. Three meta-analyses in cognitively impaired adults found small MMSE gains -- MD 1.08 overall and 2.63 in mild cognitive impairment (PMID 41185054), MD 1.48 with low-dose treatment in Alzheimer's dementia (PMID 35450525), and MD 1.82 in Alzheimer's patients treated over 12 weeks (PMID 33957167). These improvements are real but clinically marginal (roughly 1-2 MMSE points) and drawn from small trials.
The case weakens further outside dementia. Two earlier meta-analyses suggested melatonin cut ICU delirium (RR 0.72-0.75; PMID 40662882, PMID 41602948), but the larger 2025 double-blind DEMEL trial found no benefit at all (RR 0.986; PMID 40608082), undercutting that claim. In healthy adults, daytime melatonin actually reduced reaction accuracy (SMD -0.74; PMID 33957167) -- a harm signal, not a nootropic effect.
Regulators and clinics reinforce the cautious read. The FDA sees 'no basis to conclude that melatonin is GRAS,' and EFSA's only approved claims concern sleep onset, not cognition; the UK NHS treats it as prescription-only. Mayo Clinic says it 'doesn't seem to improve cognition,' Cleveland Clinic calls it possibly inappropriate for dementia patients, and the Alzheimer's Association states no supplement is proven to help -- so no authority backs melatonin for cognitive benefit.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.416
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (1 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 1 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status