L-Theanine for Sleep Quality

Research suggests that L-theanine may offer modest benefits for sleep quality, particularly in reducing the time it takes to fall asleep, improving overall sleep satisfaction, and reducing sleep disturbances, with support coming from a 2025 meta-analysis of 19 randomized controlled trials, several individual RCTs, and a range of preclinical animal studies. Studies indicate that these effects may be enhanced when L-theanine is combined with other compounds such as GABA, magnesium, or milk-derived peptides, though this makes it difficult to isolate L-theanine's specific contribution. However, the evidence is not uniformly positive — some reviews and trials describe the findings as mixed or limited in rigor, noting small sample sizes, short study durations, reliance on subjective self-report measures, and the frequent use of multi-ingredient formulations rather than L-theanine alone. Overall, while the existing body of research is promising and generally points in a supportive direction, reviewers consistently call for larger, more rigorous, and longer-duration clinical trials before firm conclusions can be drawn about L-theanine's role in improving sleep.