Melatonin, a hormone produced by the pineal gland (located in the middle of the brain), regulates thesleep-wake cycle. Melatonin used in supplements can be derived from animals, but most is produced artificially. In some countries, melatonin is considered a medication and is regulated as such.
(See also Overview of Dietary Supplements.)
Claims for Melatonin
People use melatonin mostly to treat insomnia and to help minimize the effects of jet lag or of shift work. People who are traveling across time zones may take melatonin on the day or night of departure and for 2 to 4 nights after arrival. People who rotate work shifts may take melatonin before going to bed. Research is being conducted in using melatonin to resynchronize the sleep-wake cycle for people in the early phases of Alzheimer disease, as well as for seasonal affective disorder (feeling depressed during winter months).
Melatonin is also used to manage anxiety before and after surgery; 80% of people experience anxiety prior to surgery.
Evidence for Melatonin
Evidence suggests that melatonin supplements can affect the sleep-wake cycle. Thus, melatonin supplements may help certain people with symptoms of jet lag or temporary insomnia and has been used for as long as 6 months. However, there is little evidence that melatonin effectively treats chronic insomnia.
Side Effects of Melatonin
Headache, dizziness, nausea, sleepiness, and transient depression may occur. Melatonin may increase existing depression. Whether melatonin is safe when used long-term is unknown. Melatonin is best taken under medical supervision, particularly when given to children. In people with epilepsy, melatonin may increase seizures. Melatonin may exacerbate autoimmune diseases. Also, melatonin may decrease fertility, and whether melatonin is safe in pregnancy or while breastfeeding is unknown.
Melatonin content varies among different products, and the products' labels do not always accurately state the amount of melatonin in the product.
More people are experiencing significant side effects of melatonin, sometimes requiring hospitalization, including from accidental ingestion of melatonin by children.
The American Academy of Sleep Medicine recommends older adults with dementia avoid melatonin supplements. Melatonin may stay active in older adults longer than in younger people and cause daytime drowsiness.
Drug Interactions with Melatonin
Melatoninmay increase effects of warfarin, increasing risk of bleeding.
Melatonin may enhance the sedative effects of certain medications such as benzodiazepines.
Melatonin may decrease the effects of antiseizure medications and increase the risk of seizures.
Melatonin may increase side effects ofmethamphetamine.
Some medications may affect melatoninlevels. For example, fluvoxamine, estrogens, and quinolone antibiotics may increasemelatoninlevels. Conversely, some medications (for example, the antiseizure medication carbamazepine and the antibiotic rifampin) may decreasemelatonin levels.
Recommendations for Melatonin
People with problems sleeping or who want to treat or prevent jet lag can try melatonin, but most, particularly those considering taking melatonin repeatedly, should consult with their doctor first. Melatoninshould not be taken by people with dementia, epilepsy or autoimmune diseases, women trying to become pregnant, and those taking warfarin.
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
National Institutes of Health's National Center for Complementary and Integrative Health: Melatonin: What You Need To Know
