I would assume you mean Melatonin... a naturally occuring hormone in most mammals, including humans. Its levels in humans appears to decrease with age and is linked to the ability to sleep well.
As a long haul pilot for many years, I and many other acquaintances in the aviation industry have used it to overcome "jet lag" (which is a misnomer but describes the upset of the naturally occuring
circadian rhythm we all experience caused by the crossing of numerous time zones in a short period of time). I've not noticed any side effects but I'm judicious in its use, limited to one dose (3mg) per night about 30 minutes for bed time when I'm "on the road". It's never shown any indication of dependence in my use. It's very reasonable in cost. Here's a balanced review:
http://familydoctor.org/online/famdocen/home/a rticles/258.html
As the article indicates,avoid
natural Melatonin... depend on synthetic varities if you choose to use it...