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.
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).
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).
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).