I've had sleeping probs for a long time and smoking pot only makes it worse. If I smoke in the late afternoon or evening I get so hyped I may not sleep all night. Before noon works for me. Everyone's different.
Marijuana prevents you from getting proper REM sleep so even if it does put you to sleep easier than being sober it does not necessarily put you in a state of sleep that is essential for your health. A good supplement for stoners is melatonin. It allows you to fall asleep easy, does not require you to change your smoking patterns and allows you to get the REM sleep your immune system needs.
i've read that about melatonin too. i've heard that one must have a functioning adult body to supplement with it though, and i think it recommends something like 23-25, and not any age lower than that. i've heard some good things about it regulating problems associated with weed, so it's definately worth looking into, but look into the age issue also.