Well I just started university this week, and I bought 3mg pills of melatonin, I'd take ONE pill 30 minutes to an hour before sleeping and generally I'd feel pretty tired, so it helped me fall asleep easier.
Normally I'd get 7.5-8 hours of sleep (go to bed 10-11 wake up 6-6:30) and i was always tired in classes, but by the afternoon I was a bit more awake.
Last night I went to a party, had a few drinks (I was loopy but not very drunk), and came home. I still woke up at ~6 that morning and was tired during the day, but by the time I went to sleep it was around 2:30am by my estimation. I woke up and looked at my clock and it was about 8:30, so I only slept for a total of 6 hours. However, I took 2 pills of melatonin, 6mg total, and I feel fully rested from that, even though I worked out and had a relatively active day.
Is there any explanation for this? Could 3mg of melatonin just make me tired and 6mg make me not need as much sleep. From what I've read, it just helps you sleep the amount of time you need. With being 18 and working out I should need no less than 8, up to 10 hours a night. Also I tried to fall asleep for almost an hour of just laying in my bed and couldn't.