I wake up feeling lethargic for the first couple of hours generally, body takes a while to counteract the extra 'sleep chemical' and release enough 'wake chemical'. Your brain doesn't necessarily release as much Melatonin naturally as you'll be taking, so you might take a little while to adjust. I found I was getting 'Melatonin Hangovers' in the beginning. See how your body reacts and adjust your dose, everyone is different.