Ashwagandha vs Glycine
Both are commonly discussed for sleep. Ashwagandha and Glycine both have moderate evidence — Ashwagandha edges ahead on research volume (20 vs 20 studies referenced).
Evidence last reviewed May 2026
Ashwagandha
Adaptogen
Glycine
Amino Acid
Evidence
🟡Moderate Evidence
🟡Moderate Evidence
Research says
Research agrees
Research agrees
Expert mentions
356
3 recommend
176
3 recommend
Studies
20
referenced
20
referenced
Study dose
300–600mg
The majority of positive RCTs and the meta-analytic evidence supporting stress and anxiety reduction used standardized extracts (e.g., KSM-66 or Sensoril) in the range of 300–600 mg per day, administered as a single dose or split across two doses; higher withanolide standardization (≥5%) is associated with the studied effects.
3000–15000mg
Sleep studies primarily used 3g (3000mg); the GlyNAC RCT and broader therapeutic reviews reference ranges up to 9–15g daily depending on the health outcome studied. Higher doses have been used in metabolic and aging contexts without notable adverse effects reported.
Best timing
MorningEveningWith food
EveningEmpty stomach
Who recommends
Caution
Generally safe
Generally safe
Ashwagandha
Key findings
- ·Multiple RCTs and at least one meta-analysis support statistically significant reductions in perceived stress and anxiety with ashwagandha supplementation, making this the best-evidenced use case.
- ·Cortisol reduction has been reported across several placebo-controlled trials, suggesting a plausible biological mechanism underlying the stress-relief effects.
- ·Doses of 300–600 mg per day of standardized extract, consistent with those used in positive clinical trials, are referenced across the reviewed literature as the studied therapeutic range.
Evidence gaps
- ·Long-term safety data beyond 12 weeks is largely absent, leaving the risk profile for extended supplementation — including liver health — poorly characterized.
- ·Most trials use proprietary or specific extract formulations, making it unclear whether findings generalize to the wide variety of ashwagandha products available to consumers.
Glycine
Key findings
- ·A randomized clinical trial of GlyNAC (glycine + N-acetylcysteine) in older adults found improvements in glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, and physical function, supporting glycine's role as a key substrate for glutathione synthesis.
- ·Glycine is a well-established biochemical precursor to glutathione, creatine, and collagen — three molecules with broad relevance to aging, muscle function, and tissue integrity.
- ·Glycine may be conditionally essential in older adults and under high physiological demand, as endogenous synthesis appears insufficient to meet total-body requirements in these contexts.
Evidence gaps
- ·Most clinical evidence for glycine uses combination products (e.g., GlyNAC, gelatin + vitamin C), making it impossible to determine how much of the observed benefit is attributable to glycine alone versus co-ingredients.
- ·Long-term supplementation trials in diverse human populations are lacking; existing studies are largely short-term and focused on older adults or athletes, leaving gaps for other demographics including those with chronic disease.