What side effects do people report with L-Theanine?

Most often: drowsiness, vivid dreams, fatigue, headache, anhedonia.

What else do people take for sleep?

Inositol (100% of 43), Lemon Balm (92% of 106), Taurine (92% of 99), Magnesium (88% of 443), Glycine (87% of 255).

Does L-Theanine help with sleep?

Q: Does L-Theanine help with sleep?

Often, yes. 78% of 370 people who reported on L-Theanine for sleep say it improved; 11% noticed no change and 11% say it got worse.

Often, yes. 78% of 370 people who reported on L-Theanine for sleep say it improved. 11% noticed no change and 11% say it got worse. That is below the typical result for sleep (82% across 71 options).

Sleep: what users report

78%better370 reports · high confidence

288 better42 no change40 worse

Ranked #23 of 71 for sleep.

What people say about L-Theanine and sleep

“This stuff truly works... I'm really surprised how much this supplement has helped with the generalized anxiety.”

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“I practice good sleep hygiene, but thus far I've not seen any notable improvements that are repeatable.”

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“Other sleep supplements failed at helping me (I've tried l-theanine, taurine, bacopa and ashwagandha)”

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What the research says

AResearch: Strong18 meta-analyses · 78 trials on PubMed

Nutr Rev · 2025

Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Conclusion: This meta-analysis provides evidence that theanine plus caffeine, and theanine alone, could be beneficial for cognitive and mood outcomes. More research using tea beverages or tea-equivalent bioactive doses and research in free-living participants is needed.

Sleep Med Rev · 2025

The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis

Conclusion: The findings indicate the potential use of L-theanine in the management of sleep disturbances; however, the lack of studies on "pure" L-theanine warrants further investigation. Future studies are needed to determine the adequate dose and duration of L-theanine supplementation for improving and maintaining sleep quality in healthy and clinical populations.

Side effects people mention

drowsiness 87vivid dreams 24fatigue 19headache 9anhedonia 8

What else is L-Theanine used for?

Anxiety 91%of 1,289 Focus 88%of 501 Mood 77%of 223 Energy 68%of 97 Memory 67%of 12 Libido 25%of 12 Heart & lipids 88%of 8 Pain & inflammation 100%of 5

Information only — not medical advice. How we count