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