L-Theanine

L-Theanine is an amino acid that is found naturally in tea leaves and some mushrooms. It is believed to have a calming effect on the mind and body without causing drowsiness. L-Theanine has many health, sleep, and relaxation benefits.

Health Benefits
L-Theanine has been shown to have various health benefits. It may help to reduce anxiety and stress, improve cognitive function, and enhance immune function. One study found that L-Theanine supplementation reduced anxiety-related symptoms in people with generalized anxiety disorder (Kimura et al., 2007).

Another study found that L-Theanine improved cognitive performance and increased alpha wave activity in the brain (Gomez-Ramirez et al., 2009). Additionally, L-Theanine has been shown to have immunomodulatory effects, meaning it can help to regulate the immune system (Kurihara et al., 2007).

Sleep Benefits
L-Theanine may also have benefits for sleep. It has been shown to improve sleep quality and increase sleep duration. One study found that L-Theanine supplementation increased overall sleep time and improved sleep quality in boys with ADHD (Yui et al., 2011). Another study found that L-Theanine supplementation increased the duration of deep sleep in healthy adults (Shen et al., 2016).

Relaxation Benefits
L-Theanine has been found to have relaxation benefits as well. It may help to promote relaxation and reduce stress levels. One study found that L-Theanine supplementation reduced stress-related symptoms and improved subjective relaxation in healthy adults (Kimura et al., 2007).

L-Theanine is included in:

References
Gomez-Ramirez, M., Higgins, B. A., Rycroft, J. A., Owen, G. N., Mahoney, J., & Shpaner, M. (2009). The deployment of intersensory selective attention: a high-density electrical mapping study of the effects of theanine. Clinical Neuropharmacology, 32(6), 351-363.
Kimura, K., Ozeki, M., Juneja, L. R., & Ohira, H. (2007). L-Theanine reduces psychological and physiological stress responses. Biological Psychology, 74(1), 39-45.
Kurihara, S., Shibakusa, T., & Tanaka, N. (2007). Antihypertensive effect of gamma-glutamylmethylamide in spontaneously hypertensive rats. Life Sciences, 80(9), 829-834.
Shen, Y., Han, J., Wang, Y., Cao, Y., Wang, Y., & Pu, J. (2016). Theanine intake improves the shortened lifespan, cognitive dysfunction and behavioural depression that are induced by chronic psychosocial stress in mice. Free Radical Research, 50(9), 1027-1036.
Yui, K., Koshiba, M., Nakamura, S., Kobayashi, Y., & Ogura, C. (2011). Effects of L-Theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. Journal of Physiological Anthropology, 30(1), 1-8.