Played around with this and after running it for a long time at various dosages I still can't give a solid answer. It's got a 24 hr half life so it doesn't really matter in terms of effectiveness, only thing is trying to mitigate the sides. I haven't been able to do that. I've taken the whole dose in the am, the whole dose three hours before bed, the whole dose pre workout and the whole dose before bed. I've also taken half dose am pm, pre cardio pre workout and various other half and half schemes. In the end the only thing I can say is when I first started it kept me up for a while and I had to take an hour or two pre bed, so I switched to morning. Over time it made no difference at all.