You need to take the mellie, then the niacin in order to use up all the niacin in your cells. Put the dogma that melatonin is for sleepy time out of your head. That's just what it's marketed for. It goes far beyond that - especially for gut health. You do not want to flush. If you do not flush that means the niacin was used up in your cells through the melatonin. If groggy, it's too much mellie, add niacin.