I do not find melatonin to have any day effects, then again my sleep is all screwed up, I take my melatonin at around 7 pm , take my sleeping pills at 1:30 ,a good night for me is sleeping from say 2:30- 6:00 , bad nights kinda run together 4 or 5 days at a clip with no sleep, until you just wish your head would explode ,melatonin is an interesting creature and can screw up your sleep , as well as help it , keep your doses low and use it sparingly because you can build a tolerance very quickly .