L-Theanine is a naturally occurring amino acid primarily found in green tea leaves (Camellia sinensis). It is well-known for its ability to promote relaxation, reduce stress, and improve mental focus without causing drowsiness. L-Theanine supports neurotransmitter balance, enhancing alpha brain wave activity, which contributes to a calm yet alert mental state. It is widely used in dietary supplements, functional beverages, and wellness formulations.