L-Theanine is an amino acid found naturally in tea leaves, particularly green tea, and is one of the more well-studied compounds for promoting calm without drowsiness. Research suggests that L-theanine may support relaxation by influencing alpha brain wave activity, which is associated with a state of wakeful calm and improved focus. Studies indicate it may help ease feelings of stress and anxiety while also supporting cognitive performance, particularly attention and concentration during demanding tasks. Some research has also explored its potential role in improving sleep quality, not by acting as a sedative but by helping to quiet mental restlessness that can interfere with falling asleep. Available commonly as L-theanine or the patented form Suntheanine, it remains one of the most approachable and widely researched calming amino acids.
Compare this supplementResearch suggests that L-theanine may support several aspects of cognitive function, including attention, working mem...
View studies →Research suggests that L-theanine promotes relaxation primarily by increasing alpha brain wave activity, modulating k...
View studies →Research suggests that L-theanine may offer modest benefits for sleep quality, particularly in reducing the time it t...
View studies →Research suggests that L-theanine alone may have limited direct effects on attention and focus, but studies indicate ...
View studies →L-theanine modulates the stimulant effects of caffeine, creating calm focus.
View details →Both promote relaxation and sleep through complementary, gentle mechanisms.
View details →These are commonly referenced dosage ranges for this supplement. They are not medical recommendations. Always consult a healthcare provider before supplementing.
| Form | Dose range | Frequency | Studied for | Source |
|---|---|---|---|---|
| Capsule | 100–200 mg | Daily | anxiety relief and relaxation | Common in clinical trials examining stress and anxiety reduction |
| Capsule | 100–200 mg | As needed | focus and attention, often combined with caffeine | Widely studied in combination with caffeine (typically 1:2 theanine-to-caffeine ratio) for cognitive performance |
| Capsule | 200–400 mg | Daily | sleep quality | Used in RCTs assessing sleep onset and quality improvement |
| Powder | 200–250 mg | Daily | cognitive function and general relaxation without sedation | Common dose range in RCTs measuring alpha brain wave activity and cognitive outcomes |