Rice Cakes

I have stopped taking it, but originally it went like this: start on 3mg, become tolerant and use 6mg, become tolerant and use 9mg, become disturbed that I'm tolerant to even that much, decide to skip a night or two and try to fatigue myself into sleep with low-weight/high-repetition excercise (with limited success, I always felt a little worse without melatonin...