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