L-theanine is an amino acid found primarily in green tea (also present in black tea, but at lower levels) that has potent effects on brain health and mood. Neurotransmitter support: L-theanine increases levels of GABA, serotonin, and dopamine, which help regulate mood, sleep, and emotions, promoting feelings of calm and well-being. Brain waves: It encourages alpha brain wave activity, associated with relaxed alertness, similar to meditation or creative thinking. Glutamate-like effects: Its struc