L-Theanine (also known as Theanine, L-γ-glutamylethylamide and N5-ethyl-L-glutamine) is an analog of the amino acids of glutamate and glutamine. It was discovered as a constituent of green tea in 1949 and in 1950 was isolated from gyokuro leaves, which have high theanine content.
L- Theanine is used as a nootropic for its relaxing effects. It is advisable to take in combination with caffeine as research shows it can reduce potential negative effects, such as poor sleep quality, anxiety & increased blood pressure, while possibly improving upon the positive aspects.
L-theanine increases levels of dopamine and serotonin in the brain which provides a feeling of calm and content.