I used melatonin during finals exams this week. Quite useful. I had gotten stoned sick off some powerful weed (dank) over the weekend, due to my chronic underestimation of the power of the bong to mess me up. I take too many hits, and the true power of the herb strikes me after it's too late. So, i had a wicked hangover the next day, and decided to take melatonin that night to stave off the insommnia that always affects me after a long hangover.
I swear by melatonin. With half a 3mg pill, i wake up ready to work and think, with only a small headache as a side effect. It is almost like a caffeine buzz, only without the nausea and jitters. I am probably damaging my health severely, but melatonin is a hormone naturally produced by your brain, so it is probably less dangerous than, say, amphetamines, and does not cause agressivness. Dosages vary for different people.