MSD Manual

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Laura Shane-McWhorter

, PharmD, University of Utah College of Pharmacy

Reviewed/Revised Mar 2024

Melatonin, a hormone produced by the pineal gland (located in the middle of the brain), regulates the sleep-wake cycle The sleep cycle Sleep is necessary for survival and good health, but why sleep is needed and exactly how it benefits people are not fully understood. One of sleep's benefits is its restorative effect on people's... read more . 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.

Claims for Melatonin

People use melatonin mostly to treat insomnia Insomnia and Excessive Daytime Sleepiness (EDS) The most commonly reported sleep-related problems are insomnia and excessive daytime sleepiness. Insomnia is difficulty falling asleep or staying asleep, waking up early, or a disturbance in... read more and to help minimize the effects of jet lag Circadian Rhythm Sleep Disorders Circadian rhythm sleep disorders occur when people’s internal sleep-wake schedule (clock) does not align with the earth’s cycle of darkness (night) and light (day). Jet lag and shift work commonly... read more 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 Seizure Disorders In seizure disorders, the brain's electrical activity is periodically disturbed, resulting in some degree of temporary brain dysfunction. Many people have unusual sensations just before a seizure... read more , melatonin may increase seizures. Melatonin may exacerbate autoimmune diseases Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more . 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

Melatonin may 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.

Some medications may affect melatonin levels. For example, fluvoxamine, estrogens, and quinolone antibiotics may increase melatonin levels. Conversely, some medications (for example, the antiseizure medication carbamazepine and the antibiotic rifampin) may decrease melatonin 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. Melatonin should 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.

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