Melatonin
Melatonin is a chemical that is naturally produced by the body to assist with falling asleep and remaining asleep. According to the The National Sleep Foundation, it is interesting to note that it is only released when it is dark outside, and that its levels tend to rise in the hours just before night (NSF). Not only does it make you feel drowsy, but it also keeps the levels of melatonin in your blood up for an average of 12 hours, or until the return of daylight, whichever comes first. In spite of the fact that there is no such thing as a "normal" baseline amount of melatonin, our bodies naturally produce less of the hormone as we get older, and its levels can also be affected by a variety of other factors at any point in time. Melatonin supplements, which contain a chemically manufactured version of the hormone, have been shown to promote a healthy sleep cycle.
Resources: Melatonin
