Melatonin is a hormone created by your body which assists with the sleep/wake cycle and it sold along with nutritional supplements over the counter in this country. As you grow older the levels of melatonin in the body decline. I personally don't advocate melatonin use for those under age 25 to 30 due to risk of altering natural feedback mechanisms. If you are older than that, there are two ways to utilize melatonin: first, you can use it for short periods of change in sleep time, such as jet lag and shift work. Secondly, if you want to use it for chronic sleep problems, taking it every evening at the same time is more helpful. Good luck with your insomnia issues.