I take it in the morning, every morning.
Doesn't bother me one bit. I'll take it in the morning and go have great workouts an hour later.
It gave me weird dreams, so I had to go A.M.
It wont hurt to take it with TRIBEX, and in fact I do that as well. And like most said, as long as you avoid calcium and fiber like the plague you can have food with it. Im not sure about ZMA, but I know alot of herbs, TRIBEX in particular, have better absorbtion with food.