[Kishin]

Though it is a more obvious supplement, I am surprised melatonin is not on here. Your body produces melatonin (often known as the sleep compound) naturally, and it regulates sleeping and circadian rhythm.

It is available OTC and is relatively safe to take. Don't take it every day and take a low dosage. I take it when traveling (to help with jetlag) and every once in a while just to help with sleep. It definitely puts you in a deeper sleep. Some people who take it even report more vivid dreams (and I would definitely agree).