L-Theanine is an amino acid found in tea leaves, particularly green tea (Camellia sinensis), and Mental Calmness contains pure L-Theanine (Suntheanine ). Derived from green tea using a specialized enzymatic process, Suntheanine L-Theanine does not cause daytime drowsiness. It provides help for persons who have trouble falling asleep and staying asleep because their minds refuse to shut down at night. Being calm also facilitates weight control because emotional stress is a major reason why many overeat.