A dietary supplement that helps promote a restful state. L-Theanine has shown the ability to promote deep muscle relaxation and improved quality of sleep. Its known for its calming effects in the brain and is shown to support increased concentration and focus while reducing irritability. DaVincis L-Theanine is the Suntheanine® brand, which means it is 100% pure L-Theanine in a patented, pharmaceutical grade form.