The Ultimate Guide to Melatonin: Dosage, Benefits, and Side Effects

benefits of melatonin

Melatonin is a hormone that is naturally produced in the pineal gland of the brain, which regulates the sleep-wake cycle. But did you know that there are many other benefits of melatonin? In this article, we’ll explore the various health conditions that melatonin may help, including sleep disorders, neurodevelopmental disorders, COVID-19, neuroinflammation, mental illness, detoxification, mast cell activation syndrome, endometriosis, fertility, and cancer.

Conditions Melatonin may Benefit

Neuropsychiatric Disorders

Sleep: The most well-known benefit of melatonin is its ability to improve sleep quality. Research has found that taking melatonin supplements can help people fall asleep faster, improve sleep duration, and enhance the overall quality of sleep. Dosing varies for sleep. Melatonin is typically dosed between 1-3 mg, taken 30-60 minutes before bedtime. If it is being used to treat a delayed circadian rhythm (night owl), lower doses are often used in the range of 0.3-0.5mg up to 5-6 hours before bedtime.

ADHD and Autism: Melatonin supplementation has been found to improve sleep quality in people with ADHD and autism, and improve daytime symptoms. The mechanism is likely by reducing neuroinflammation (mechanism below). Studies have shown melatonin can reduce symptoms of hyperactivity, anxiety, and repetitive behaviors in children with autism. The dose for neurodevelopmental disorders will vary from 2-10mg per day.

Neuroinflammation (aka inflammation of the brain and nervous system): Neuroinflammation is an inflammatory response in the brain that can contribute to various neurodegenerative diseases, such as Alzheimer’s, Parkinson’s disease, ADHD, mental illness, and more. Researchers have found that melatonin possesses anti-inflammatory properties that can reduce neuroinflammation and potentially slow down the progression of these diseases. The optimal dosage for reducing neuroinflammation is higher than that for sleep improvement, generally ranging from 5-20 mg per day.

Mental Illnesses: Researchers have found that melatonin possesses antidepressant and anti-anxiety effects. Some studies suggest that melatonin may help regulate the production of serotonin, a neurotransmitter that is often low in people with depression. The optimal dosage for depression is generally 1-5 mg per day.

GI Disorders

IBS/IBD: Studies have shown that melatonin improves gut motility. It can also reduce visceral hypersensitivity, which commonly causes chronic pain with these conditions. Melatonin’s anti-inflammatory and antioxidant properties may help reduce the inflammation and oxidative stress that contribute to the symptoms of IBS and IBD.

Immune Disorders

Mast Cell Activation Syndrome (MCAS)/Histamine Intolerance: Researchers have found that melatonin has a stabilizing effect on mast cells themselves. It’s anti-oxidant and anti-inflammatory effects can also be helpful for reducing symptoms of MCAS.

Cancer: There is some research suggesting that high-dose melatonin may have potential benefits for hormone-sensitive cancers, such as breast and prostate cancer. A study published in the journal Cancer Chemotherapy and Pharmacology in 2016 found that high-dose melatonin (20 mg/day) had potential benefits for prostate cancer patients undergoing androgen deprivation therapy. The study found that high-dose melatonin helped to improve sleep quality, reduce anxiety, and improve quality of life in these patients.

Covid-19: Melatonin was one of the first supplements researchers considered during the Covid-19 pandemic.

  • Acute Covid: Melatonin appears to help by it’s action as an antioxidant, anti-inflammatory, and immune modulator.
  • Chronic/long-haul Covid: Melatonin can be helpful in reducing chronic inflammation, improving sleep, and reducing neurological symptoms associated with long haul.

Detoxification: Studies have shown that melatonin enhances the activity of several key enzymes involved in the brain’s detoxification pathways. The cytochrome P450 system is responsible for brain detoxification by eliminating toxins. It can increase glutathione levels (the body’s master antioxidant) and support detoxification of mold mycotoxins, heavy metals, and more.

Reproductive Disorders

Endometriosis: A 2013 randomized controlled trial found that high daily doses of melatonin had benefits for women with endometriosis. The women who took the melatonin used less pain medication and cramping, painful intercourse, and bowel pain all improved. It is likely helpful via the anti-inflammatory and anti-oxidant pathways listed above. The dose for endometriosis is typically 10mg nightly, as tolerated.

Fertility: Melatonin has potential benefits for both men and women. Melatonin helps regulate the menstrual cycle and improve the quality of oocytes (eggs) in women. In men, it improves sperm quality and quantity.

Side Effects of Melatonin

While generally very safe and well-tolerated, melatonin can have side effects as follows:

  1. Too much, too fast: Melatonin can be a powerful agent, and sometimes it is too rapidly detoxifying for the person to tolerate. Starting with a low dose and increasing slowly will decrease likelihood of side effects. Taking too much melatonin can lead to negative side effects, such as headaches, dizziness, grogginess, and nausea. It is important to follow the recommended dosage and consult with a healthcare provider before taking melatonin.
  2. Timing: Melatonin supplements should be taken at the appropriate time for optimal effectiveness. Taking melatonin too early or too late in the day can disrupt the body’s natural sleep-wake cycle and lead to side effects.
  3. Nightmares or vivid dreams: Melatonin’s ability to increase time in REM sleep may lead to more vivid dreams or nightmares. If unpleasant dreams are occurring, address possible underlying factors as nightmares are also associated with high stress and trauma.
  4. Quality of the Supplement: Not all melatonin supplements are created equal. Some supplements may contain inconsistent amounts of melatonin or other ingredients that can interfere with its effectiveness. Always source melatonin from companies that are transparent about third party testing.


Melatonin is a powerful hormone with anti-oxidant and anti-inflammatory benefits that can impact numerous health conditions. It is recommended to support your body’s own production of melatonin first, and consult with a healthcare provider regarding supplementation due to its detoxifying nature and potential interactions with some medications.


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