L-Theanine promotes Relaxation & Helps Control Emotions w/o drowsiness It is by far the best natural product I have used that not only promotes a relaxed, calm state, but helps me control my emotional roller coasters during certain times of the month!! It does NOT make me sleepy, just calms me down! I use any where from 100mg, 200mg, to 400mg. depending on my level of stress! It is a natural substance-an amino acid!! It’s healthy for the brain, and may even improve your ability to learn & enjoy pleasure!! It effects the Dopamine & Serotonin neurotransmitters in the brain in a POSITIVE way!! As with any other supplement, you should ask your doctor before starting this if you are in a doctor’s care or taking any prescription medications!! I HIGHLY RECOMMEND THIS PRODUCT!! While I don’t specifically endorse any specific brand, as I use the least expensive, choose one from a reputable company and you should be fine!