L-Theanine vs Melatonin
Both are commonly discussed for sleep. L-Theanine and Melatonin both have moderate evidence — Melatonin edges ahead on research volume (20 vs 20 studies referenced).
Evidence last reviewed May 2026
L-Theanine recommends stacking with Melatonin: Low-dose melatonin targets circadian rhythm signaling while L-theanine may promote relaxation, making the combination appealing for sleep onset support
Melatonin recommends stacking with L-Theanine: L-Theanine promotes relaxation without sedation and may help reduce sleep-onset anxiety when combined with melatonin's circadian phase-setting properties.
L-Theanine
Amino Acid
Melatonin
Hormone
Evidence
🟡Moderate Evidence
🟡Moderate Evidence
Research says
Research agrees
Research agrees
Expert mentions
191
3 recommend
216
3 recommend
Studies
20
referenced
20
referenced
Study dose
100–400mg
Studies across anxiety, sleep, and cognitive outcomes have generally used doses in the 100–400 mg range, with many individual experts noting personal use around 100–200 mg; optimal dose may vary by goal and individual sensitivity.
0mg
The body's endogenous nightly output is approximately 0.1–0.3 mg; studied supplemental doses range from 0.5 mg (sufficient for phase-shifting per expert consensus) up to 10 mg (common OTC doses), though lower doses of 0.5–1 mg are considered more physiologically appropriate for general sleep onset by clinical experts, as higher doses may blunt receptor sensitivity over time.
Best timing
MorningEvening
EveningEmpty stomach
Who recommends
Caution
Generally safe
Generally safe
L-Theanine
Key findings
- ·Multiple systematic reviews suggest L-theanine may modestly reduce subjective stress and anxiety, but effect sizes are generally small and study quality is variable.
- ·A systematic review and meta-analysis on sleep found some supportive evidence for L-theanine improving sleep outcomes, though results were not uniformly strong.
- ·The L-theanine and caffeine combination appears to be the best-supported application, with reviews noting potential reduction in caffeine-induced jitteriness and possible cognitive benefits.
Evidence gaps
- ·There is a lack of large, well-powered, long-term RCTs in general adult populations, meaning chronic effects on anxiety, sleep, and cognition remain poorly characterized.
- ·Optimal dosing, timing, and formulation of L-theanine supplementation have not been systematically established across studies, limiting practical guidance.
Melatonin
Key findings
- ·Melatonin is consistently characterized across multiple reviews as a chronobiotic hormone — a darkness signal produced by the pineal gland — not a sedative or sleep drug.
- ·A meta-analysis on dietary supplements found melatonin associated with improvements in sleep quality outcomes, representing one of the stronger evidence-based applications.
- ·A systematic review and meta-analysis supports melatonin use in ICU patients, suggesting potential benefits in this specific clinical population.
Evidence gaps
- ·Long-term safety and efficacy data for melatonin supplementation in healthy adults and children are largely absent from the reviewed literature, leaving many dosing and duration questions unanswered.
- ·Most reviewed studies are narrative reviews or general overviews rather than large, well-controlled RCTs, making it difficult to establish causality or optimal dosing protocols for specific conditions.