L-theanine is an amino acid that helps promote a restful, relaxed state without diminishing daytime alertness.* It's free of the side effects commonly associated with other relaxing agents and can  be used to aid in stress management.

During a study of human volunteers, L-theanine promoted the generation of alpha brain waves, an indication of relaxation.* Another small, controlled clinical trial suggests that L-theanine supports a healthy stress response.* Results of yet another human trial suggest that L-theanine may act via the sympathetic-medullary system, either in addition to or instead of the hypothalamic-pituitary-adrenal axis.* L-theanine has long thought to interact with the binding of L-glutamic acid to glutamate receptors in the brain.*