L-Theanine for ADHD
Amino acid from tea leaves that crosses the blood-brain barrier and increases alpha-wave brain activity; promotes calm alertness without sedation, often paired with caffeine.
L-Theanine for ADHD
4 of 7 results reported a benefit, from 3 published studies.
3 studies, including a review of trials · the chart counts everything measured
- 4 reported a benefit
- 1 no clear benefit
- 1 unclear
- 1 possible harm
Colour keyReported a benefitNo clear benefitUnclearPossible harmAmber is for highlights, such as where the most research is. It never means a result was good.
Nothing measured ADHD directly. These were measured:
- Sleep efficiencyReported a benefitL-theanine improved sleep efficiency compared to baseline.1 review of trials · no comparable figure reported2 of 2 results reported a benefit2025 study ↗
- Impulse-control reaction timeReported a possible harmsee exact figuresL-Theanine showed harm (adverse effect) on inhibitory control (Stop-signal reaction time) compared with placebo in five boys (8-15 years) (~ 1 h post-dose).1 randomised trial2020 study ↗
- Overall thinking skillsReported a benefitsee exact figuresL-Theanine improved total cognition composite compared with placebo in five boys (8-15 years) (~ 2 h post-dose).1 randomised trial2020 study ↗
- Percentage of time asleepReported a benefitmeasurement not reportedL-theanine (Suntheanine®) improved Sleep percentage compared with placebo in 98 (six weeks).1 randomised trial2011 study ↗
- Time awake during the nightUnclear resultmeasurement not reportedL-theanine (Suntheanine®) showed an unclear effect on Activity during sleep (time awake after sleep onset) compared with placebo; the difference versus placebo was not statistically established in 98 (six weeks).1 randomised trial2011 study ↗
- Time to fall asleepNo clear benefit foundmeasurement not reportedL-theanine (Suntheanine®) did not significantly improve Sleep latency compared with placebo; the difference versus placebo was not statistically established in 98 (six weeks).1 randomised trial2011 study ↗
These are the figures the studies reported, not a prediction for any one person. Where several studies measured the same thing in the same unit, we show a simple average and say so. Every result is listed below.
See every resultThe connection
Attention-deficit/hyperactivity disorder: persistent inattention, hyperactivity or impulsivity that disrupts daily life.
Also known as: Theanine, L-gamma-glutamylethylamide
L-Theanine × ADHD: at a glance
Every published result for this pair, extracted and audited.
These charts count reported findings from published studies, grouped by reported benefit and study design. Study design is not a certainty grade.
L-Theanine / ADHD: reported findings; one study may contribute several findings.
What the evidence shows
What this means: Counts describe research quantity, not treatment effectiveness or certainty.
| Category | Findings (count) |
|---|---|
| Benefit | 4 |
| Harm / risk | 1 |
| Unclear | 1 |
| No benefit | 1 |
Study designs behind these findings
What this means: Counts describe research quantity, not treatment effectiveness or certainty.
| Category | Findings (count) |
|---|---|
| Systematic review | 1 |
| Randomised trial | 6 |
- Studies
- 3
| Study | Outcome | Reported result | Uncertainty (as reported) | Study duration |
|---|---|---|---|---|
| Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of Stimulants: A Systematic Review. (PMID 40362791) | Sleep efficiency | Not reported | Not reported | Not reported |
| Effects of L-theanine-caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT. (PMID 32753637) | inhibitory control (Stop-signal reaction time) | Not reported | p = 0.053 | ~ 1 h post-dose |
| Effects of L-theanine-caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT. (PMID 32753637) | total cognition composite | Not reported | p = 0.040 | ~ 2 h post-dose |
| The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. (PMID 22214254) | Activity during sleep (time awake after sleep onset) | Not reported | Not reported | six weeks |
| The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. (PMID 22214254) | Sleep efficiency scores | Not reported | Not reported | six weeks |
| The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. (PMID 22214254) | Sleep latency | Not reported | Not reported | six weeks |
| The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. (PMID 22214254) | Sleep percentage | Not reported | Not reported | six weeks |
Study results, as reported by the publications
Every measured outcome, one row per finding - numbers exactly as reported. Units are preserved where supplied; missing units are not inferred.
| Study and type | Reported sample and duration | Outcome measured | Reported result | What studies found |
|---|---|---|---|---|
| PMID 40362791 2025 Systematic review | Sample (as reported): Not reportedDuration: Not reported | Sleep efficiency | Not reported | Benefit |
| PMID 32753637 2020 Randomised trial | Sample (as reported): five boys (8-15 years)Duration: ~ 1 h post-dose | inhibitory control (Stop-signal reaction time) | Not reported (p = 0.053) | Harm / risk |
| PMID 32753637 2020 Randomised trial | Sample (as reported): five boys (8-15 years)Duration: ~ 2 h post-dose | total cognition composite | Not reported (p = 0.040) | Benefit |
| PMID 22214254 2011 Randomised trial | Sample (as reported): 98Duration: six weeks | Activity during sleep (time awake after sleep onset) | Not reported | Unclear |
| PMID 22214254 2011 Randomised trial | Sample (as reported): 98Duration: six weeks | Sleep efficiency scores | Not reported | Benefit |
| PMID 22214254 2011 Randomised trial | Sample (as reported): 98Duration: six weeks | Sleep latency | Not reported | No benefit |
| PMID 22214254 2011 Randomised trial | Sample (as reported): 98Duration: six weeks | Sleep percentage | Not reported | Benefit |
L-Theanine × ADHD: the evidence base
Hand-selected PubMed studies, linked to the originals.
Ordered by strength of evidence, then result direction.
01Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of Stimulants: A Systematic ReviewAl Shahab S, et al. · Nutrients · 2025PMID 40362791 ↗02Safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder: A systematic review and network meta-analysisZhou P, et al. · PloS one · 2024PMID 38547138 ↗03The effects of L-theanine supplementation on the outcomes of patients with mental disorders: a systematic reviewMoshfeghinia R, et al. · BMC psychiatry · 2024PMID 39633316 ↗04Polyunsaturated fatty acids (PUFA) for attention deficit hyperactivity disorder (ADHD) in children and adolescentsGillies D, et al. · The Cochrane database of systematic reviews · 2023PMID 37058600 ↗05Association between sleep pattern and pharmacological treatment in children with attention deficit disorder with hyperactivity: a systematic reviewRocha NS, et al. · Revista paulista de pediatria : orgao oficial da Sociedade de Pediatria de Sao Paulo · 2023PMID 37255110 ↗06Omega-3 Polyunsaturated Fatty Acids for Core Symptoms of Attention-Deficit/Hyperactivity Disorder: A Meta-Analysis of Randomized Controlled TrialsLiu TH, et al. · The Journal of clinical psychiatry · 2023PMID 37656283 ↗Community experiences
Contributors volunteered; this does not establish treatment effectiveness or population incidence.
Reported changes
No publishable community breakdown is available. This does not establish that no reports exist.