L-Theanine: A Natural Support for Relaxation, Sleep, and Cognitive Function

Rectangle 505
L-Theanine: A Natural Support for Relaxation, Sleep, and Cognitive Function

L-theanine is a naturally occurring amino acid that is commonly found in tea leaves, especially green tea. This supplement has gained popularity in recent years for its potential benefits, including improved focus and relaxation.

One of the primary benefits of L-theanine is its ability to promote relaxation without causing drowsiness. A study published in the Journal of Functional Foods found that L-theanine supplementation significantly reduced stress and anxiety levels in participants, leading to improved cognitive performance and overall mood. (1)

L-theanine may also have a positive effect on sleep quality. A study published in the Journal of Clinical Neurology found that L-theanine supplementation improved sleep quality in participants with anxiety disorders. (2)

In addition to its calming effects, L-theanine has also been shown to enhance focus and cognitive function. A study published in Nutritional Neuroscience found that L-theanine supplementation improved attention and reaction time in participants completing a cognitive task. (3)

L-theanine may also have potential benefits for individuals with high blood pressure. A study published in the European Journal of Nutrition found that L-theanine supplementation decreased blood pressure in participants with high-normal blood pressure. (4)

Dosage recommendation:

Most patients start with 100mg orally every 4 hours as needed.  The majority of patients find 200mg-400mg/dosage to be well tolerated and effective. To improve absorption, like all amino acid based supplements, L-Theanine is best taken on an empty stomach.

Overall, L-theanine is a promising supplement with potential benefits for relaxation, sleep quality, cognitive function, and blood pressure. As with any supplement, it's important to talk to your healthcare provider before starting L-theanine supplementation.


  1. Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007;74(1):39-45.
  2. Hidese S, Ogawa S, Ota M, et al. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients. 2019;11(10):2362.
  3. Einöther SJL, Martens VEG, Rycroft JA, De Bruin EA. L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness. Appetite. 2010;54(2):406-409.
  4. Park SK, Jung IC, Lee WK, et al. A combination of green tea extract and L-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study. J Med Food. 2011;14(4):334-343.