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Head-to-head evidence comparison — which supplement is right for you?
L-Theanine wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
10 of 10 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
3 of 4 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (3)
Outcomes where both Ashwagandha and L-Theanine have evidence — compare verdict strength side-by-side.
300-600mg daily (standardized extract)
Morning for daytime stress, Evening for sleep support
KSM-66 or Sensoril standardized extract
100-200mg
Morning with coffee for focus, Evening for relaxation, As needed for stress
Suntheanine® capsules or powder
2-4 weeks
2-4 weeks
2-4 weeks
First week
30-60 minutes
30-60 minutes
30-60 minutes
Varies
Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis
Journal of the American Nutrition Association (2024) · Meta analysis · n=873
Significant reduction in HAM-A anxiety scores (p=0.0007)
Effects of Withania somnifera Extract in Chronically Stressed Adults: A Randomized Controlled Trial
Nutrients (2024) · Rct · n=131
Our findings demonstrate the stress-reduction capabilities of this well-characterized aqueous extract of WS (root and leaf) at the low dose of 125 mg/day, in a dose-dependent manner, via the modulation of the HPA axis.
Plant-derived nootropics and human cognition: A systematic review
Critical reviews in food science and nutrition (2023) · Systematic review
Bacopa monnieri improves language, learning and memory.
The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis
Sleep medicine reviews (2025) · Meta analysis · n=897
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.
Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of Stimulants: A Systematic Review
Nutrients (2025) · Systematic review
The evidence revealed the potential use of supplements as complementary ADHD treatments under clinical guidance.
Analysis of the Effects of Known Sleep-Support Supplements in Relation to Life Habits, Sleep Conditions, and Sleep Problems
Nutrients (2023) · Rct · n=160
All the tested supplements were found to ameliorate sleep problems significantly (Analysis 1).
Based on meta-analysis showing significant HAM-A score reduction (p=0.0007) and RCT evidence at 125mg dose. High heterogeneity (I2=98%) in pooled analysis suggests variable response. Extract standardization affects bioavailability.
Meta-analysis (n=897) and multiple RCTs support sleep benefits. Studies often used L-theanine in combination with other compounds, limiting pure L-theanine effect attribution. Effects include reduced sleep onset latency and improved subjective sleep quality.
AI-estimated from published studies. Interpret as directional guidance.
L-Theanine has a higher evidence score (9/10 vs 7.5/10) and wins in 2 of 3 categories.
For reduce anxiety & stress, Ashwagandha has a higher relevance score (95 vs 85).
No known interactions between Ashwagandha and L-Theanine have been documented in our database. However, always consult a healthcare provider before combining supplements.