Natural melatonin is predominantly made in your pineal gland, which is located in your brain. Light exposure inhibits the production of melatonin, but darkness stimulates it.
Melatonin levels in your brain begin to increase at dusk as the sun goes down and darkness falls. They reach their peak levels in the middle of the night and start decreasing as dawn gets closer.
The action of melatonin inhibits signals in your brain that promote wakefulness. This helps encourage sleep by making you feel tired or drowsy as you get closer to bedtime.
Because of melatonin’s sleep-promoting effects, melatonin supplements are used to treat a variety of sleep problems. These can include:
The Food and Drug Administration (FDA) doesn’t regulate melatonin as a drug. Because of this, there’s limited information on the optimal, safe dosage of melatonin.
In fact, the doses of melatonin supplements that have been used in various scientific studies vary widely, from 0.1 to 10 milligrams (mg). One 2017 review defines a typical dose of melatonin to be between 1 and 5 mg.
Melatonin typically takes 1 to 2 hours to work, so it’s often taken up to 2 hours before bedtime.
If you’re looking to try melatonin for the first time, it may be best to begin with a lower dose. Your doctor can help recommend a safe dose for you to start with.
Melatonin for children
Like melatonin for adults, there’s not much information on the optimal, safe dosage for children. Dosage may also vary depending on a child’s age. One 2016 review suggests the following age-based dosages 30 to 60 minutes before bedtime:
- 1 mg for infants
- 2.5 to 3 mg for older children
- 5 mg for adolescents
Because there aren’t clear dosing guidelines regarding melatonin for children, be sure to speak to your child’s pediatrician before giving melatonin to your child.
Melatonin for older adults
The amount of melatonin your body produces decreases with age. Because of this, melatonin supplements may be helpful for older adults who are having trouble falling asleep.
Researchers are still looking into the optimal melatonin dosage for older adults. One 2016 review of sleep aids for older adults suggests a dosage of 1 to 2 mg of immediate-release melatonin 1 hour before bedtime.
What to know about dietary supplements and safety
The FDA classifies melatonin as a dietary supplement, meaning that it’s regulated less strictly than a regular drug. For dietary supplements, label claims and product safety don’t have to meet FDA approval before they’re marketed.
A 2017 study of 31 different melatonin supplements found that the actual melatonin content of 71 percent of the products didn’t match the claim on the label. Additionally, 26 percent of products contained serotonin, which can be potentially harmful even in small doses.
When shopping for melatonin supplements, look for products that are “USP verified.” United States Pharmacopeia (USP) is an independent organization that works to ensure proper quality and dosing of dietary supplements.
According to the National Center for Complementary and Integrative Health (NCCIH), short-term use of melatonin supplements appears to be safe for most adults and children. However, information on the effects of long-term melatonin supplements is limited.
Some studies have indicated that long-term melatonin use in adults may cause mild side effects when compared to a placebo. Studies into the effects of long-term melatonin use in children remains limited.
Because melatonin levels naturally decrease at the beginning of puberty, there’s some concern that long-term melatonin use in children may delay puberty onset. However, more research is needed.
Melatonin is generally safe. However, mild side effects can sometimes occur, particularly if you take higher doses or extended-release formulations.
The side effects of melatonin can include:
Some less common side effects of melatonin include:
- abdominal cramps
- mild tremors
- feelings of depression or anxiety
- confusion or disorientation
- low blood pressure (hypotension)
You may be wondering what happens if you take a dose of melatonin and find that you still can’t fall asleep. Can you take another dose?
While taking an additional dose is unlikely to cause harm, it may increase your risk for experiencing unwanted side effects.
If you find that melatonin isn’t helping you fall asleep, stop using it. Your doctor may be able to suggest different medications or strategies to help you fall asleep.
There are some important things to know about melatonin, its interactions with other substances, and when it’s best to avoid it. Let’s take a closer look.
What medications and substances does melatonin interact with?
Melatonin may interact with several different types of medications, including:
- Blood-thinning medications. Taking melatonin with blood-thinning medication may increase your risk for bleeding.
- Epilepsy medications (anticonvulsants). Melatonin may make these medications less effective.
- Immunosuppressants. Melatonin can potentially interfere with immunosuppressive drugs.
- Diabetes medications. Melatonin use can affect blood sugar levels.
- Blood pressure medications. Blood pressure may get worse when melatonin is taken with these medications.
- Contraceptive drugs. Birth control pills may increase the risk of side effects from melatonin.