Melatonin is produced by the pineal gland located in the brain. The pineal gland senses light. In the absence of light, the body will produce more melatonin; while light will decrease melatonin production and start the waking process.

Occurring naturally in the body, this hormone helps to regulate sleep and is commonly used for treating insomnia and jet lag.

Scientists are investigating melatonin's usefulness in seasonal affective disorder, improving sleep for shift workers, and combating chronic cluster headaches.

Many references suggest avoiding melatonin use in infants, children, or while pregnant or breastfeeding. Use melatonin with caution or consult a health practitioner if you have pre-existing medical conditions (such as high blood pressure, seizures, fertility issues, elevated blood sugars, depression, issues with bleeding or immune function).

The verdict is still out with regard to benefits of long term use as a sleep aid. Some studies suggest melatonin produces only a modest effect at improving time to sleep and length of sleep. Additional studies indicate that 0.3mg nightly is an adequate dose, and that higher doses for longer periods of time may actually cause the hormone to stop working.