Melatonin is a common dietary supplement that has gained widespread popularity around the globe.
Though renowned as a natural sleep aid, it also has powerful effects on other aspects of your health.
This article reviews the benefits and potential side effects of melatonin, as well as its best dosage.
Melatonin is a hormone produced by the pineal gland in your brain (1).
Therefore, it’s often used as a sleep aid to combat issues like insomnia.
It’s widely available in the US as an over-the-counter medication but requires a prescription in other parts of the world, such as Europe and Australia.
Plus, it acts as an antioxidant, with some research finding that it can significantly affect many health conditions.
Summary Melatonin is a hormone responsible for regulating your body’s sleep cycle. It’s also associated with other health benefits.
Melatonin is often called the sleep hormone — and for good reason.
It’s one of the most popular sleep aids and a common natural remedy to treat issues like insomnia.
Multiple studies have demonstrated that melatonin can support better sleep.
One study in 50 people with insomnia showed that taking melatonin two hours before bed helped people fall asleep faster and enhanced overall sleep quality (7).
Another large analysis of 19 studies in children and adults with sleep disorders found that melatonin reduced the amount of time it took to fall asleep, increased total sleep time and improved sleep quality (8).
However, though melatonin is associated with fewer side effects than other sleep medications, it may be less effective (8).
Summary Studies show that melatonin can lengthen total sleep time, shorten the amount of time it takes to fall asleep and enhance sleep quality in children and adults.
Seasonal affective disorder (SAD), also called seasonal depression, is a common condition that is estimated to affect up to 10% of the population worldwide (9).
This type of depression is related to changes in the seasons and occurs each year around the same time, with symptoms typically appearing in late fall to early winter.
Some research indicates that it could be linked to changes in your circadian rhythm caused by seasonal light changes (10).
Because melatonin plays a role in regulating circadian rhythm, low doses are often used to decrease symptoms of seasonal depression.
According to one study in 68 people, alterations in circadian rhythm were shown to contribute to seasonal depression, but taking melatonin capsules daily was effective at reducing symptoms (5).
However, other research is still inconclusive on the effects of melatonin on seasonal depression.
For instance, another review of eight studies showed that melatonin was not effective at reducing symptoms of mood disorders, including bipolar disorder, depression and SAD (11).
Further research is needed to determine how melatonin may impact symptoms of seasonal depression.
Summary Seasonal depression may be related to changes in your body’s circadian rhythm. One study found that melatonin capsules may help reduce symptoms, but other research is inconclusive.
Some studies have found that supplementing with melatonin may increase levels of HGH in men.
One small study in eight men found that both low (0.5 mg) and high (5 mg) doses of melatonin were effective at increasing HGH levels (15).
Another study in 32 men showed similar results (16).
However, larger-scale studies are needed to understand how melatonin may affect levels of HGH in the general population.
Summary Some studies have found that taking melatonin may increase levels of HGH in men, but more research is needed.
Melatonin is high in antioxidants that can help prevent cell damage and keep your eyes healthy.
In fact, research suggests that melatonin could be beneficial in treating conditions like glaucoma and age-related macular degeneration (AMD) (17).
In a study in 100 people with AMD, supplementing with 3 mg of melatonin for 6–24 months helped protect the retina, delay age-related damage and preserve visual clarity (4).
Additionally, a rat study found that melatonin decreased the severity and incidence of retinopathy — an eye disease that affects the retina and can result in vision loss (18).
However, research is limited and additional human studies are needed to determine the effects of long-term melatonin supplements on eye health.
Summary Melatonin is high in antioxidants and has been shown to treat eye conditions like age-related macular degeneration and retinopathy in human and animal studies.
Melatonin has been shown to block the secretion of stomach acids. It also decreases the production of nitric oxide, a compound that relaxes your lower esophageal sphincter, allowing stomach acid to enter your esophagus (20).
For this reason, some research suggests that melatonin may be used to treat heartburn and GERD.
One study in 36 people showed that taking melatonin alone or with omeprazole — a common GERD medication — was effective at relieving heartburn and discomfort (6).
Another study compared the effects of omeprazole and a dietary supplement containing melatonin along with several amino acids, vitamins and plant compounds in 351 people with GERD.
After 40 days of treatment, 100% of people taking the melatonin-containing supplement reported a reduction in symptoms compared to only 65.7% of the group taking omeprazole (20).
Summary Melatonin can block stomach acid secretion and nitric oxide synthesis. Studies show that it may be effective at reducing heartburn and GERD symptoms when used alone or with medication.
Melatonin can be taken in doses of 0.5–10 mg per day.
However, because not all melatonin supplements are the same, it’s best to stick to the recommended dosage on the label to avoid adverse side effects.
You may also want to start with a lower dose and increase as needed to find what works for you.
If you’re using melatonin to improve sleep quality, try taking it 30 minutes before bedtime for maximum effectiveness.
Meanwhile, if you’re using it to correct your circadian rhythm and establish a more regular sleep schedule, you should take it about 2–3 hours before you go to bed.
Summary Melatonin can be taken in doses of 0.5–10 mg per day up to three hours before bedtime, though it’s best to follow the recommended dosage listed on the label of your supplement.
Research shows that melatonin is safe and non-addictive for both short- and long-term use in adults (21).
However, because long-term studies on the effects of melatonin are limited to adults, it’s not currently recommended for children or adolescents (24).
If you’re taking any of these medications, talk to your doctor before taking melatonin to prevent adverse effects.
Summary Studies show that melatonin is safe and associated with minimal side effects in adults but may interact with certain medications.
Melatonin may improve sleep, eye health, seasonal depression, HGH levels and GERD.
Doses of 0.5–10 mg per day appear to be effective, though it’s best to follow label recommendations.
Melatonin is safe and associated with minimal side effects, but may interact with some medications. It’s currently not recommended for children.