amino acid · for insomnia
L-Theanine
Shifts your brain toward the calm state that comes just before sleep.
Say that in clinical terms
L-theanine promotes alpha brain wave production, facilitating the transition from wakefulness to sleep. It increases GABA and serotonin levels while reducing excitatory glutamate, creating a neurochemical environment conducive to sleep onset.
How strong is the research?
Evidence evidence
Only one studyIndustry fundedLow-quality evidence
1 paper read, 1 supporting.
Who was studied: The best-powered sleep trial was in 98 boys aged 8 to 12 with ADHD. That is a long way from an adult who cannot sleep.
How much to take
daily, 30-60 min before bed
200–400 mg
Promotes relaxation without sedation. Safe to use nightly. Can be combined with magnesium for enhanced effect.
Before you take it
- No NIH/IOM Tolerable Upper Intake Level (UL) has been established for L-theanine; it is a non-essential amino acid with no Dietary Reference Intake framework.
- May potentiate the blood-pressure-lowering effect of antihypertensive medications through additive hypotensive effects; clinically relevant for users on antihypertensive drugs.
- Insufficient safety data exist for use during pregnancy and lactation; the NIH advises against supplemental L-theanine use when pregnant or nursing a preterm or newborn infant.
- FDA has granted GRAS status to L-theanine for use in specific food/beverage categories at specific commercial doses; this does not constitute a safety ceiling for all supplemental doses or populations.
- The cited paper is a manufacturer-authored narrative review (all 3 authors Taiyo Kagaku employees) and is not primary clinical evidence; it cannot substitute for independent RCT data for the insomnia association. Users with clinical insomnia should be directed to CBT-I (first-line evidence-based treatment) rather than supplements.