L-Theanine is a naturally occurring, unique amino acid found in green tea leaves. NuMedica’s L-Theanine is Suntheanine® – the most respected source and the one which has been used in scientific studies. L-Theanine may promote a sense of relaxation without causing drowsiness. It has also been found to promote healthy cellular function and reduce feelings of stress and anxiety. L-Theanine may be useful in reducing the negative side effects of caffeine.