Melatonin is a hormone produced in the brain’s pineal gland at night that plays a role in the body’s sleep-wake cycle, preparing the body for sleep as it gets dark.
Many people take melatonin supplements in the hope of sleeping better without the side effects that can accompany prescription and over-the-counter sleep aids. Melatonin is also sometimes taken to help with jet lag, stress, and aging. Melatonin supplements are marketed as “natural” sleep aids, though it does not mean they are harmless.
The Food and Drug Administration (FDA) considers melatonin to be a dietary supplement, which means melatonin supplements are not required to undergo the same kind of rigorous research and testing as prescription and over-the-counter sleep aids. Because of this, there can be a wide variety in supplements.
Differences in preparation can result in a significantly different impact on the body, even for the same dosage. In addition, dosages listed on supplement labels are often inaccurate and do not contain the labeled dose. Consumers can find reliable formulations by looking for United States Pharmacopeial Convention Verified labels.
There is not a one-size-fits all ideal dose of melatonin. Dosing and response to the hormone can vary from one individual to another based on age, gender, time the supplement is taken, the person’s sleep problems, and other underlying health issues. For example, elderly people may be more sensitive to the effects of melatonin supplements and should take the lowest possible dose.
Melatonin supplements can be purchased without a prescription, and common doses range from 0.1 to 10 milligrams, though 2 to 3 milligrams are usually considered an appropriate initial dose. Melatonin is generally considered safe with typical use in healthy adults.
Side effects of melatonin use are uncommon but may include:
For melatonin, higher doses are not necessarily better, and excess melatonin can pose health risks. Symptoms of too much melatonin may include:
- Headache
- Hypotension (low blood pressure)
- Hypertension (high blood pressure)
- Drowsiness
- Vomiting
- Worsening of alopecia areata (an autoimmune disorder causing hair loss)
- May induce depression in people who have depression or who are predisposed to it (however, some studies have shown melatonin may be used in some people to help treat depression)
- Increased seizures in patients with epilepsy
Melatonin may also interact with blood thinners and benzodiazepines.
There are some reports that suggest that long-term melatonin use may affect reproductive hormones.