Melatonin is a hormone naturally produced by most animals, including humans, as well as by some other organisms, such as rice and algae. Melatonin helps to regulate the body's circadian rhythms, biological functions that follow a roughly 24-hour cycle. Because of this, melatonin for sleep is available as a supplement in the United States, Canada, and the United Kingdom. You can take melatonin for sleep as an alternative to prescription or over-the-counter drugs.
Though humans naturally produce melatonin, some people may not produce as much as they need. The major sites of melatonin synthesis in humans include the skin, the retina, and the pineal gland, and the mechanism of production is triggered by darkness. In the modern world, most people have much less exposure to darkness than our ancestors did because of artificial lighting. Wearing light-blocking goggles in the hours before bed may help to naturally increase melatonin levels, but some people choose to take melatonin for sleep instead.
Melatonin for sleep can help with circadian rhythm disruptions such as jet lag, delayed sleep phase syndrome, and non-24-hour sleep-wake syndrome. It is often used in conjunction with light therapy in the morning. Melatonin supplements are typically taken 30 to 90 minutes before bedtime. In addition to naturally regulating the sleep cycle, melatonin supplements may have antioxidant and immune-boosting properties.
Some side effects of melatonin for sleep include headaches, grogginess, nausea, hormone fluctuations, and vivid dreams or nightmares. The vivid dreams, however, may be attributable to the Vitamin B6 included in many over-the-counter melatonin supplements. The risk of any side effects is increased for large doses, such as more than 3 mg/day. While 3 mg is a typical over-the-counter dose of melatonin, some studies have suggested that it is up to ten times the effective amount. One should not operate heavy machinery or drive when taking melatonin, as with any sleep aid. Melatonin supplements are not available without a prescription or at all in most countries.
A 2006 Canadian study found that melatonin is safe for short term use, up to three months. However, they did not find significant differences between melatonin supplements and a placebo, either in effectiveness or adverse side effects. If you are considering adding melatonin or other dietary supplements to your daily regimen, make sure to discuss your choice with your doctor first.