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

Journal: Sleep medicine reviews

Volume: 81

Issue: 

Year of Publication: 

Affiliated Institutions:  Faculty of Health, University of Canberra, Bruce, Canberra, ACT, , Australia; Functional Foods and Nutrition Research (FFNR) Laboratory, University of Canberra, Bruce, Canberra, ACT, , Australia; University of Canberra Research Institute of Sport and Exercise (UCRISE), University of Canberra, Canberra, ACT, , Australia. Faculty of Health, University of Canberra, Bruce, Canberra, ACT, , Australia; Functional Foods and Nutrition Research (FFNR) Laboratory, University of Canberra, Bruce, Canberra, ACT, , Australia; Centre for Ageing Research and Translation, University of Canberra, Canberra, ACT, , Australia. Food & Mood Centre, IMPACT-The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Deakin University, Barwon Health, Geelong, VIC, , Australia. Faculty of Health, University of Canberra, Bruce, Canberra, ACT, , Australia. Faculty of Health, University of Canberra, Bruce, Canberra, ACT, , Australia; Functional Foods and Nutrition Research (FFNR) Laboratory, University of Canberra, Bruce, Canberra, ACT, , Australia; University of Canberra Research Institute of Sport and Exercise (UCRISE), University of Canberra, Canberra, ACT, , Australia; Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, , South Africa. Faculty of Health, University of Canberra, Bruce, Canberra, ACT, , Australia; Functional Foods and Nutrition Research (FFNR) Laboratory, University of Canberra, Bruce, Canberra, ACT, , Australia; University of Canberra Research Institute of Sport and Exercise (UCRISE), University of Canberra, Canberra, ACT, , Australia; Discipline of Nutrition-Dietetics, Harokopio University, Athens, , Greece. Electronic address: Nenad.Naumovski@canberra.edu.au.

Abstract summary 

This systematic review ansd meta-analysis aimed to evaluate the effects of L-theanine, a non-proteinogenic amino acid found in tea, on sleep outcomes. Literature searches were conducted in five electronic databases (APA PsycINFO, CINAHL, Medline, Scopus, Web of Science), and one register (Cochrane Central Register of Controlled Trials) from inception until September 2024. Randomised controlled trials investigating the effects of L-theanine supplementation on sleep quality in humans of all ages and health status were included. Nineteen articles (N = 897 participants) were selected and 18 included in the meta-analysis. L-theanine was shown to significantly improve subjective sleep onset latency (SMD = 0.15, 95 % CI [0.01, 0.29], p = 0.04; n = 10 studies), subjective daytime dysfunction (SMD = 0.33, 95 % CI [0.16, 0.49], p < 0.001; n = 9 studies), and overall subjective sleep quality score (SMD = 0.43, 95 % CI [0.04, 0.83], p = 0.03; n = 12 studies). 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.

Authors & Co-authors:  Bulman Amanda A D'Cunha Nathan M NM Marx Wolfgang W Turner Murray M McKune Andrew A Naumovski Nenad N

Study Outcome 

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Statistics
Citations : 
Authors :  6
Identifiers
Doi : 10.1016/j.smrv.2025.102076
SSN : 1532-2955
Study Population
Male,Female
Mesh Terms
Other Terms
Green tea;L-theanine;Meta-analysis;Nutraceuticals;Sleep;Systematic review
Study Design
Study Approach
Systemic Review
Country of Study
Publication Country
England