In supplement form, it is often taken alone or with caffeine, and has been investigated in human clinical trials for its effects on psychological and cognitive well-being.
How does it work?
- Calming without sedation: Promotes relaxation by increasing alpha brain wave activity, associated with a calm state of alertness.
- Stress modulator: Lowers cortisol levels and reduces physiological reactivity to stress.
- Improved sleep: Facilitates the onset of sleep and improves its quality, without altering the normal cycle or causing drowsiness the next day.
- Cognitive support: Promotes sustained attention, mental focus and working memory, especially in demanding situations.
Benefits according to science
Stress and anxiety reduction
Several clinical trials have shown thatTaking 200–400 mg of L-Theanine daily can reduce anxiety and stressin healthy people, without causing drowsiness.
A trial in adults with chronic stress showedsignificant improvements in anxiety levels,sleep qualityand alsomild symptoms of depression decreased.
A 2019 systematic review also foundConsistent positive effects on mood, anxiety, and mental calm.
Improved sleep
Although not a sedative, L-Theanine improves sleep quality, especially in people with stress or mild insomnia.
For example, some clinical trials have shownimprovements in sleep qualitywith L-Theanine supplementation, especially in people with mild stress or insomnia.
Cognitive function and attention
Several trials show that L-Theanineimproves concentrationand themental performanceIn healthy middle-aged adults, asignificant improvement in sustained attention, hereaction timeand theworking memoryafter one month of supplementation.
In combination with caffeine, it has also been shown to increase processing speed and reduce errors in divided attention tasks, i.e., paying attention to more than one stimulus at a time.
Mood disorders
Some studies suggest that L-Theanine may be useful as an adjunctive treatment for people with generalized anxiety or mild depression. In a controlled trial in patients with generalized anxiety disorder, supplementationimproved sleep and reduced anxiety, although the effect was slight.
Another more recent systematic review from 2024 also supports its use asmental health adjuvant, although it emphasizes the need for more specific studies.
L-Theanine is anatural supplementwith scientific support forreduce stress,improve sleepand support themental concentrationwithout causing drowsiness. Itssafety profile is excellentand its use is especially useful for active people, with a high stress load or with mild anxiety or sleep problems.
As always, it is recommendedprofessional supervisionif other treatments are being taken or there are pre-existing medical conditions.
La L-teanina favorece la atención sostenida, el enfoque mental y la memoria de trabajo.
La L-teanina favorece el inicio del sueño y mejora su calidad.
La L-teanina disminuye los niveles de cortisol y reduce el estrés
