L-Theanine Supplementation & HRV (N=1 Data)
200 mg/day L-theanine: a 2019 crossover RCT in healthy adults reported lower depression/anxiety self-ratings and better PSQI sleep-quality scores vs placebo, plus verbal-fluency gains; separate ring-based N=1 logs report ~+11 ms HRV with replicated washouts.
PubMed crossover anchor (stress, sleep questionnaire, cognition)
Hidese et al. 2019 (Nutrients; PMID 31623400; hidese-2019-l-theanine-stress-cognition-rct) tested 200 mg/day tablets × 4 weeks vs placebo in 30 healthy adults: SDS, STAI-trait, and PSQI improved vs placebo, with PSQI subscales (latency, disturbance, medication use) also favoring theanine; verbal fluency / executive function improved—read the full text for industry tablet supply and crossover caveats (small n, questionnaire-tier sleep).
N=1 Evidence (wearable HRV)
- Maveric78: 200 mg/day L-Theanine
- HRV: +11 ms above baseline
- Replicated ×2 with 4-week washout between trials
- HRV returned to baseline after stopping
- Duration: 1 week onset per trial
Double replication with washout — strongest supplement methodology in dataset.
Tertiary map
Wikipedia: Theanine (wikipedia-theanine-overview) covers tea chemistry, supplement regulation, and mixed review quality (EFSA health-claim assessments, recent review skepticism)—stack next to the Hidese RCT for tiered evidence, not as a substitute for primary outcomes tables.
Evidence
- N=1 Reports on rapamycin.news
- Wikipedia: Theanine
- Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial
- Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study