L-Theanine
An amino acid from tea that promotes relaxation via GABA and alpha waves.
L-theanine improves subjective sleep quality and reduces anxiety without causing drowsiness
L-theanine (200mg daily) improves subjective sleep quality and reduces anxiety in adults with high anxiety levels. Unlike many sleep aids, it does not cause daytime drowsiness and promotes relaxation via alpha-wave enhancement.
L-theanine supplementation significantly improves subjective sleep quality, sleep onset latency, and daytime dysfunction.
This systematic review and meta-analysis of 19 RCTs (N=897) found that L-theanine significantly improved subjective sleep onset latency (SMD=0.15, 95% CI [0.01, 0.29], p=0.04), subjective daytime dysfunction (SMD=0.33, 95% CI [0.16, 0.49], p<0.001), and overall subjective sleep quality score (SMD=0.43, 95% CI [0.04, 0.83], p=0.03). The findings suggest potential use for managing sleep disturbances, but further research is needed on pure L-theanine and optimal dosing.
L-theanine supplementation improves subjective sleep quality, reduces sleep onset latency, and decreases daytime dysfunction.
A systematic review and meta-analysis of 19 RCTs (N=897 participants) found that L-theanine significantly improved subjective sleep onset latency (SMD=0.15, 95% CI [0.01, 0.29], p=0.04), subjective daytime dysfunction (SMD=0.33, 95% CI [0.16, 0.49], p<0.001), and overall subjective sleep quality score (SMD=0.43, 95% CI [0.04, 0.83], p=0.03). The findings suggest potential use for managing sleep disturbances, but further research is needed on pure L-theanine and optimal dosing.
Theanine plus caffeine improves cognitive and mood outcomes in healthy participants
This meta-analysis of 15 RCTs found small-to-moderate benefits of theanine plus caffeine over placebo on cognition and mood outcomes, including choice reaction time (SMD -0.48 at 1 hour) and digit vigilance task accuracy (SMD 0.20 at 2 hours). Theanine alone also showed a small-to-moderate benefit on choice reaction time (SMD -0.35 at 1 hour). However, confidence intervals were wide, indicating uncertainty in effect magnitude.
Chamomile and L-theanine beverage reduces menstrual pain and improves mood and sleep quality in young women with primary dysmenorrhea
A randomized, double-blind, placebo-controlled study found that daily consumption of a chamomile and L-theanine beverage (CTT) for five days around menstruation significantly reduced pain intensity by 57.17% (VAS) and 55.46% (NRS) compared to baseline. The intervention also significantly decreased severity of lower abdominal pain, back pain, depression, irritability, and daytime dysfunction by 31-56% in young women with primary dysmenorrhea.
Walnut peptide and theanine combination (WPT) improves chronic stress-induced sleep disorders by restoring slow-wave sleep duration and quality in adults with poor sleep quality.
In an 8-week randomized, placebo-controlled human trial, WPT restored sleep duration and improved subjective sleep quality scores (PSQI โฅ 7). Mechanistically, WPT reduced serum corticosterone levels and increased GABA and tryptophan in CUMS mice, indicating HPA axis regulation and neurotransmitter modulation.
Green tea and its bioactive compounds may improve mood disorder symptomology, particularly symptoms of depression, but no evidence to date reports effects on BDNF.
A systematic review of 13 RCTs found that green tea, green tea extract, L-theanine, and EGCG improved depressive symptoms in 4 studies, anxiety in 6, stress in 5, and sleep in 1. No studies found a statistically significant effect on brain-derived neurotrophic factor (BDNF).
L-theanine improves sleep quality and reduces stress markers in individuals with mild to moderate sleep disturbances
This study protocol describes a randomized, double-blind, placebo-controlled trial evaluating the effects of L-theanine (100mg, 200mg, 400mg) on sleep and stress markers in 60 healthy adults aged 18-65 with mild to moderate sleep disturbances. The primary outcomes are changes in objective and subjective sleep quality parameters and secondary outcomes include biochemical, physiological, and subjective stress markers after a 14-day intervention. The trial aims to determine the optimal dose of L-theanine for improving sleep and stress.
Green tea and its bioactive compounds (EGCG, L-theanine) may improve mood disorder symptomology, particularly symptoms of depression, but no evidence supports effects on BDNF.
A systematic review of 13 RCTs found that green tea, green tea extract, L-theanine, or EGCG improved depressive symptoms in 4 studies, anxiety in 6, stress in 5, and sleep in 1. No studies reported statistically significant effects on brain-derived neurotrophic factor (BDNF).
Walnut peptide and theanine combination (WPT) improves sleep disorders in adults with poor sleep quality
In an 8-week randomized, placebo-controlled human trial, WPT restored sleep duration and improved subjective sleep quality scores as assessed by the Pittsburgh Sleep Quality Index (PSQI) in adults with PSQI โฅ 7. The intervention also reduced waking activity in zebrafish and restored slow-wave sleep duration and delta wave power density in CUMS mice, while lowering serum corticosterone and increasing GABA and tryptophan levels.
High-dose L-theanine-caffeine combination improves selective attention in acutely sleep-deprived young adults
A double-blind, placebo-controlled crossover trial found that a combination of 200 mg L-theanine and 160 mg caffeine significantly improved hit rate (P=0.02) and target-distractor discriminability (P=0.047) in a visual selective attention task compared to placebo. The combination also produced a significantly greater pre-post-dose reaction time improvement (38.1 ms, P=0.003) and enhanced P3b ERP amplitudes with reduced latencies.
L-theanine supplementation at 200-450 mg/day supports healthy sleep in adults
A systematic review of 13 trials (n=550) found that L-theanine at 200-450 mg/day appears safe and effective for improving sleep in adults. Beneficial effects were reported on sleep latency, maintenance, efficiency, perceived satisfaction, and feelings of refreshment upon waking.
Theanine alleviates sleep disturbances and depression induced by sleep deprivation through neuroinflammation reduction
Theanine, a phytochemical from Camellia sinensis, exerts therapeutic effects on mental disorders caused by cumulative stress, including mild sleep disturbances and depression induced by sleep deprivation. The neuroprotective mechanism involves alleviating neuroinflammation. The paper reviews literature from the past 5 years.
Theanine alleviates sleep disturbances caused by cumulative stress
Theanine exerts therapeutic effects on mental disorders caused by cumulative stress, ranging from mild sleep disturbances to depression induced by sleep deprivation. The review covers literature from the past 5 years on the neuroprotective functions of theanine.
L-theanine improves sleep efficiency in individuals with ADHD
The systematic review found that L-theanine supplementation improved sleep efficiency but did not affect other sleep parameters in individuals with ADHD. This suggests a specific benefit for sleep quality in this population, though overall effects on ADHD symptoms were limited.
Combined GABA and L-theanine supplementation improves sleep quality in adults with sleep problems
A 4-week single-arm study of 19 adults with sleep problems found that combined intake of 700 mg/day GABA and 200 mg/day L-theanine significantly improved total PSQI score from 9.42 to 6.26 (mean difference -3.15, 95% CI -4.01 to -2.31, p < 0.001). Sleep recovery scores and heart rate during sleep also showed significant improvements.
The polyphenol/caffeine ratio determines the arousal-inducing properties of green tea ethanol extract in mice
The study found that the ratio of total phenolic content (TPC) to caffeine in green tea ethanol extract (GE) strongly correlates with arousal-inducing effects, with an Rยฒ of 0.9428. Specifically, the EGCG/caffeine ratio was closely associated with sleep duration (Rยฒ = 0.9034), and combining L-Theanine with EGCG slightly strengthened this correlation (Rยฒ = 0.9464). The extract with 58.9 mg gโปยน caffeine induced arousal comparable to 25 mg kgโปยน caffeine in mice.
l-Theanine improves learning and memory by inhibiting NOX4-mediated ferroptosis in hippocampal neurons of sleep-deprived mice
In sleep-deprived mice, l-theanine treatment significantly increased the frequency of crossing the platform in the Morris water maze, indicating improved learning and memory. It also protected hippocampal neurons and mitochondria, reversed abnormal expression of ferroptosis-related proteins (e.g., NOX4, GPX4, ACSL4), and mitigated oxidative stress in HT22 cells. The neuroprotective effects were reversed by the GLX351322 agent, confirming the role of NOX4 inhibition.
White tea accelerates re-entrainment to phase advances, while dark and black tea improve adaptation to phase delays in mice
In a mouse model of circadian disruption, white tea markedly accelerated re-entrainment to a 6-hour phase advance, whereas dark and black tea improved adaptation to a 6-hour phase delay. Dark tea also exerted the most prominent modulation of core clock genes across tissues. In vitro, tea polyphenols, theophylline, and EGCG prolonged circadian periods and enhanced adaptation to long cycles.
l-Theanine improves learning and memory in sleep-deprived mice by inhibiting NOX4-mediated ferroptosis in hippocampal neurons
l-Theanine treatment significantly increased the frequency of mice crossing the platform in the Morris water maze, indicating improved learning and memory. It also protected hippocampal neurons and mitochondria, reversed abnormal expression of ferroptosis-related proteins, and mitigated oxidative stress in HT22 cells. The neuroprotection was reversed by the GLX351322 agent, confirming the role of NOX4.
L-Theanine inhibits neuroblastoma cell proliferation via uptake through Slc38a1
L-Theanine inhibited proliferation of NSC-34 mouse motor neuron-like hybrid cells most effectively among neural cell lines tested. This inhibition was completely alleviated by co-administration of ฮฑ-(methylamino) isobutyric acid or leucine, suggesting theanine uptake occurs via Slc38a1 and excretion via Slc7a5. The inhibition persisted even without glutamine and did not correlate with mTOR phosphorylation changes.
L-theanine prevents myocardial injury in sleep-deprived mice by suppressing ferroptosis through SIRT1
L-theanine alleviated sleep deprivation-induced tachycardia, restored myocardial and mitochondrial integrity, and reduced oxidative damage markers including ROS and Fe2+ in H9c2 cells. The protective effect was counteracted by the SIRT1 inhibitor EX-527, indicating that L-theanine mitigates cardiac injury primarily by suppressing ferroptosis through SIRT1 in cardiomyocytes.
L-Theanine inhibits neuroblastoma cell proliferation via Slc38a1 uptake
L-Theanine inhibited proliferation of NSC-34 mouse motor neuron-like hybrid cells, with complete alleviation by co-administration of ฮฑ-(methylamino) isobutyric acid or leucine, suggesting uptake via Slc38a1 and excretion via Slc7a5. Inhibition occurred even without glutamine and did not correlate with mTOR phosphorylation changes.
White tea accelerates re-entrainment to 6-hour phase advances in mice
In a mouse model of circadian disruption, white tea markedly accelerated re-entrainment to a 6-hour phase advance. Dark and black tea improved adaptation to 6-hour phase delays. Dark tea exerted the most prominent modulation of core clock genes across tissues.