Is Melatonin Bad for You?

Melatonin is safe for most people when taken over the short term, but there is not much research available yet on its long-term safety. People considering using melatonin should be aware of its potential side effects. Melatonin can cause drowsiness, so people should avoid using heavy machinery or driving after taking it. Melatonin can also interact with certain medications. 

Children, pregnant and breastfeeding people, and people with dementia should be cautious about taking melatonin or avoid it altogether. And parents and guardians should take care to keep melatonin out of the reach of young children.

What Is Melatonin?

Melatonin is a naturally occurring hormone. It is produced by the pineal gland, in the center of the brain, and is released when it is dark. Daily cycles of high and low melatonin levels help align the body’s circadian rhythms to darkness and light. 

During the daytime, when it is light and sunny, the pineal gland makes less melatonin. At night, when it is dark, melatonin levels rise and make a person feel tired. But bright lights at night are linked to lower melatonin levels and sleep difficulties.

Melatonin supplements may help people with naturally low levels of melatonin to sleep more easily. They can also help people with jet lag align their circadian rhythms to their local time zones. People with other circadian rhythm sleep disorders may also benefit from melatonin. Melatonin is occasionally used for chronic pain and depression, but research has not proven its effectiveness for these conditions.

When to Be Cautious About Taking Melatonin

People considering starting melatonin should talk with their doctors about whether melatonin will be safe and effective for them. Health experts have specific safety concerns about melatonin use by children, pregnant and breastfeeding people, and older adults with dementia. 

• Children: Parents and caregivers should talk to their child’s doctor before giving melatonin to children. The long-term safety of melatonin in children and teens is not yet fully understood. Some experts have concerns that melatonin supplements could interfere with puberty Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source or with children’s immune systems. Melatonin should also be stored where young children cannot reach and accidentally ingest it.
• People who are pregnant or breastfeeding: Not enough research is available to determine whether melatonin is safe during pregnancy and breastfeeding. People who are pregnant or trying to become pregnant should talk to their doctors before taking melatonin.
• Older adults: People with dementia and their caregivers should be careful about using melatonin. Melatonin may stay in older people’s systems Trusted Source Merck Manual First published in 1899 as a small reference book for physicians and pharmacists, the Manual grew in size and scope to become one of the most widely used comprehensive medical resources for professionals and consumers. View Source longer than in younger people, making them feel drowsy during the daytime.

People should be cautious about taking melatonin for conditions for which it has not been proven effective. Although melatonin supplements can help some sleep disorders related to circadian rhythm, it is not effective for all such disorders. For example, melatonin is not proven to help sleep difficulties related to shift work.

Some people take melatonin for seasonal affective disorder, other forms of depression, and chronic pain. However, scientific evidence does not support the use of melatonin for these conditions. In addition, melatonin is not a proven treatment for COVID-19.

What Are the Side Effects of Melatonin?

Potential side effects of melatonin include drowsiness, dizziness, nausea, and headache. Some people may experience brief periods of depression, or worsening symptoms of pre-existing depression, after taking melatonin.

Other side effects of melatonin may include:

• Realistic dreams and nightmares
• Upset stomach
• Irritable mood
• High or low blood pressure
• Problems breaking down dietary sugars

Side effects may occur more often after taking higher doses of melatonin and among people with chronic health conditions Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source .

Does Melatonin Interact With Prescription Drugs?

Melatonin can interact with certain prescription medications in various ways. People considering taking melatonin should discuss their current medications with their doctors.

• Antiseizure drugs: Melatonin may lower the effectiveness of antiseizure drugs and raise the risk of seizures among people taking them.
• Blood thinners: Melatonin can make blood clot more slowly, increasing the risk of bleeding for people taking blood thinners and anti-platelet drugs.
• Diabetes medicine: Melatonin may lower blood sugar levels Trusted Source Medline Plus MedlinePlus is an online health information resource for patients and their families and friends. View Source . This could cause blood sugar levels to drop too low when used in combination with diabetes medications.
• Blood pressure medicine: Melatonin can lower blood pressure. Blood pressure levels may fall dangerously low when people take melatonin supplements together with blood pressure medicine.
• Immune-suppressing medicine: Melatonin may stimulate the immune system. People who take medicines to weaken their immune system should avoid melatonin, including people who have received a transplant.
• Sleep aids and sedatives: Melatonin may cause excessive sleepiness in combination with other sleep aids or sedatives.

In addition, some other medications can increase melatonin levels in the body. People should take caution when taking the following substances together with melatonin supplements:

• Caffeine
• Birth control pills
• Certain antidepressants

How Can Melatonin Help You Sleep?

When taken over the short term, melatonin may help people with several sleep-related conditions.

• Insomnia: Taking melatonin before bedtime can help people with insomnia fall asleep more quickly, but it does not help people stay asleep.
• Jet lag: Melatonin supplements can reduce symptoms of jet lag among people traveling across time zones. Studies have found that travelers who take melatonin before bedtime sleep longer, have higher-quality sleep, and feel more alert during the daytime than those who do not.
• Delayed sleep-wake phase syndrome: Melatonin may help people with delayed sleep-wake phase syndrome to align their circadian rhythms with the daily cycles of light and darkness. Studies have found that people with this condition were able to fall asleep about a half hour earlier after taking melatonin, compared with people who took a placebo. 
• Non-24-hour sleep-wake disorder: Bedtime melatonin is the main treatment for blind people with non-24-hour sleep-wake disorder. Melatonin can help these people fall asleep faster, sleep longer, and nap less during the daytime.

Melatonin supplements are generally most effective when taken 1 to 2 hours before bedtime.

Typical melatonin dosage for most adults ranges from 1 to 5 milligrams Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source . Parents and caregivers should talk to their doctors about the appropriate dosage for children or teens, as younger children typically need smaller dosages than teens or adults. Doctors often recommend starting at the lowest dose available, then slowly increasing the dose only if needed.

What Are Other Ways to Get Good Sleep?

People who wish to improve their sleep should pay attention to their sleep hygiene. Establishing healthy sleep habits can help people sleep more easily, feel better, and be more productive during the day.

• Follow a sleep-wake schedule: Go to bed and wake up at consistent times every day, including weekends and holidays.
• Spend time outside in the morning: Sunlight signals the body to wake up and reinforces circadian rhythms.
• Exercise daily: Regular exercise can improve sleep quality and help people fall asleep more quickly. 
• Avoid caffeine in the late afternoon and evening: Caffeine can remain in the system and interfere with sleep for up to eight hours after drinking it.
• Avoid alcohol before bedtime: While alcohol can make people feel sleepy, sleep is lighter, lower quality, and involves more nighttime awakenings after drinking alcohol.
• Avoid afternoon naps: Long naps after 3 p.m. can make it harder to fall asleep at bedtime.
• Relax before bed: Establish a relaxing bedtime routine, such as reading, taking a bath, or listening to gentle music.
• Keep the bedroom cool, quiet, and dark: Keep bright, loud, or distracting items such as phones or tablets out of the bedroom and consider ear plugs or an eye mask for noisy or light-filled environments.

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