http://en.wikipedia.org/wiki/Melatonin#Medical_usesMelatonin has been studied as a potential treatment of gastroesophageal reflux disease,[72] cancer, immune disorders, cardiovascular diseases, depression, seasonal affective disorder (SAD), circadian rhythm sleep disorders, sexual dysfunction[73] and insomnia in the elderly.[73][74][75][76] Prolonged release melatonin has shown good results in treating insomnia in older adults (2007).[77] It may improve circadian misalignment and SAD.[78][79] Basic research indicates that melatonin may play a role in modulating the effects of drugs of abuse such as cocaine.[80][81] Melatonin is also a geroprotector.[82]
A 2004 review found that melatonin significantly increased total sleep time in people suffering from sleep restriction.[39]
Short and long term treatment of prolonged-release melatonin was found to be effective and safe, improving sleep latency, sleep quality and daytime alertness in insomnia patients.[10]
In exploratory studies, prolonged-release melatonin has shown sleep quality improvement in patients with chronic schizophrenia[83] as well as in patients with major depressive disorder[84][85] and treating sleep-wake cycle disorders in children with underlying neurodevelopment difficulties.[86][87] Additionally, as add-on to antihypertensive therapy, prolonged-release melatonin improved blood pressure control in patients with nocturnal hypertension as shown in a randomised double-blind placebo controlled study.[88]
http://sleepfoundation.org/sleep-topics ... age/0%2C1/Because it is not categorized as a drug, synthetic melatonin is made in factories that are not regulated by the FDA. Listed doses may not be controlled or accurate, meaning the amount of melatonin in a pill you take may not be the amount listed on the package. Most commercial products are offered at dosages that cause melatonin levels in the blood to rise to much higher levels than are naturally produced in the body. Taking a typical dose (1 to 3 mg) may elevate your blood melatonin levels to 1 to 20 times normal.
For melatonin to be helpful, the correct dosage, method and time of day it is taken must be appropriate to the sleep problem. Taking it at the "wrong" time of day may reset your biological clock in an undesirable direction. How much to take, when to take it, and melatonin's effectiveness, if any, for particular sleep disorders is only beginning to be understood.