Melatonin: Dosage, Reviews & Safety

Melatonin is a hormone found naturally in the body and made synthetically to promote sleep. It is also a popular supplement used for treating insomnia.  Even though there is no conclusive evidence on its effectiveness,  sales of melatonin in the US exceeded a billion dollars in 2019.  Like all supplements and medications, users should understand the drug’s uses, side effects, interactions, and dosages.

What is Melatonin?

Melatonin is a hormone found naturally in the body and is made synthetically as a sleep aid. It’s often available in pill form, but it’s also available in forms that can be placed in the cheek or under the tongue with the goal of increasing effectiveness. Some manufacturers even offer melatonin gummies. 

Man sleeping restfully

What is Melatonin Used For?

People use melatonin supplements to adjust the body’s internal clock. It is used for jet lag, for adjusting sleep-wake cycles in people whose daily work schedule changes (shift-work disorder), and for helping blind people establish a day and night cycle. Melatonin is naturally-made, has a low side-effect profile, and there is substantial scientific evidence showing its efficacy.

Melatonin has also been studied for the treatment of cancer, immune disorders, cardiovascular diseases, depression, seasonal affective disorder, and sexual dysfunction. The results of most of these studies remain inconclusive. However, it has been shown to clearly ameliorate seasonal affective disorder and circadian misalignment, in studies by other researchers.

Man taking melatonin supplement

The Science Behind Melatonin

Melatonin , chemically N-acetyl-5-methoxytryptamine, is a substance found in animals, plants, fungi and bacteria. In animals, it’s a hormone that anticipates the daily onset of darkness.

In animals, melatonin is involved in the synchronization of the circadian rhythms of physiological functions including sleep timing, blood pressure regulation, seasonal reproduction and many others. Many of its biological effects in animals are produced through activation of melatonin receptors, while others are due to its role as a pervasive and powerful antioxidant, with a particular role in the protection of nuclear and mitochondrial DNA.

The hormone can be used as a sleep aid and in the treatment of some sleep disorders. It can be taken orally in liquid form as well as capsules or tablets in immediate- or prolonged-release form. It is also available in a form to be used sublingually, and as transdermal patches. Melatonin is sold as an over-the-counter sleep aid in the U.S. and Canada. In other countries it may require a prescription or it may be unavailable.

Melatonin is referred to by some biochemists and human physiologists as the master hormone because it regulates the production of paracrine and endocrine. In addition,  when taken alone, melatonin is an immunoregulator that somewhat enhances T cell production. However, when melatonin is taken in conjunction with calcium, it is a very potent immunostimulator of the T cell response. This is the reason it is used extensively as an adjuvant in many treatment protocols. Because it does not have to be prescribed, and since it is in the public domain, few doctors care to publicize its advantages. For the same reason, few clinical trials have been done to see its effectiveness in treating various diseases, such as cancer, obesity, HIV infection, and others.

Woman taking dose of melatonin

Melatonin Dosage for Sleep

The dosage of melatonin may range from 0.3 to 10 milligrams. 

Light therapy may advance the phase about one to two-and-a-half hours and an oral dose of 0.3 or 3 mg, timed correctly a few hours before bedtime, can add about 30 minutes to the ~2 hour advance achieved with light therapy. There is no difference in the average magnitude of phase shift induced by the two doses (0.3 or 3 mg).

Melatonin Reviews

It is important to realize that melatonin is sold over the counter and that the FDA (U.S. Food and Drug Administration) does not evaluate these products for efficacy. They take action against companies that mis-brand their products or adulterate them. There are very few or large research studies that assess the efficacy of different brands.

Popular Melatonin Brands

Natrol Melatonin

Natrol Melatonin 10 mg

Nature Made Melatonin 5 mg

Herbalicious Melatonin

Herbalicious Melatonin 0.3 mg

Most reviews of melatonin products come from individual consumers who have not participated in a randomized and ‘double-blind’ trial to determine the efficacy of the products. Therefore, most melatonin reviews on the internet are not scientific in nature. But they can be used in your own research as you determine which melatonin product is right for you. 

Melatonin with a glass of water

Is Melatonin Safe?

Melatonin taken with MAOI drugs can also lead to overdose because MAO is inhibit the breakdown of it by the body. Fortunately, melatonin exhibits almost no toxic side effects, except for the occurrence of somnolence in most of the population at higher doses.(5)  There are as of yet no reports about melatonin toxicity, notwithstanding the dosage administered, nor the amount of time the medication has been taken, except for clinical changes as noted in various studies. Exogenous melatonin does not affect the endogenous profile in the short or medium-term. There have not been sufficient studies done on pregnant women concerning possible carcinogenic effects of melatonin. Learn more about melatonin side effects.

Melatonin Side Effects

Although melatonin is generally safe, it’s important to consider potential side effects with any supplement. 

Some of the most common side effects of melatonin include:

  • Daytime sleepiness
  • Dizziness
  • Headaches
  • Nausea
  • Irritability
  • A “hangover-like” feeling the next day
  • Feelings of depression while taking melatonin
  • Worsening of bleeding in those with bleeding disorders
  • Increased blood pressure in those who are taking certain blood pressure medications
  • May increase the risk for seizures in those with a seizure disorder

Possible Melatonin Interactions

In addition to the side effects of melatonin, users should also be aware of potential interactions between melatonin and other medicines. 

  • melatonin and sedatives
  • melatonin and birth control
  • melatonin and caffeine
  • melatonin and fluvoxamine
  • melatonin and antidiabetes drugs
  • melatonin and immunosuppressants
  • melatonin and anticoagulants
  • melatonin and benzodiazepines

Woman sleeping restfully

Alternatives to Melatonin

For people trying to find solutions to help them fall asleep, other alternatives to melatonin should be considered. There are medication and non-medication treatment options for people who have difficulty falling asleep or staying asleep.

Non-Medication Alternatives to Melatonin

Sleep hygiene and cognitive behavioral therapy are non-medication tools that can be used to facilitate sleep onset and continuous uninterrupted sleep. They work by helping to train the individual to sleep more efficiently.

Sleep hygiene refers to recommendations that promote a healthy conducive environment and mindset for sleep. They include having a quiet, dark and cool bedroom, avoiding stimulants before sleep and keeping a regular sleep schedule.

Programs such as Sleepstation deliver cognitive behavioral therapy online. They follow a science backed approach to deliver the most effective natural solution for a better night’s sleep. They can help you pinpoint the root issue underlying your sleep problem and provide a multi-step plan plus dedicated support to help you overcome it. You’ll also get direct access to their expert team of doctors and sleep coaches. Click here to visit their site.

Can You Overdose from Melatonin?

Many wonder, how much melatonin is too much.  The toxicity of a substance is often measured using LD50, a standard used for all types of chemical substances.  The higher the LD50 number, the less toxic the substance.  Measured on laboratory rats,  the LD50 for melatonin is 3.2 g/kg, which compares to 3.0 g/kg for table salt.   If those lab rats were the size of a typical human adult, the LD50 would be 224 grams of melatonin.  The recommended dosages listed above are well below these limits.  More is not always better, and in a high enough dose any substance can be fatal.

Melatonin Summary

In summary, melatonin is an important part of normal sleep-wake homeostasis in all mammals. Synthetic melatonin supplements are commonly used as a sleep-inducing aid. Research has demonstrated conflicting evidence about the efficacy of melatonin for the treatment of certain sleep disorders.


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12 thoughts on “Melatonin: Dosage, Reviews & Safety

  1. Beverely Reply

    I have been taking 6 10mg of Melatonin every night for a while now to get me to sleep.

  2. Heidi Reply

    To the author, can you share the source that you found the LD50 and toxicity information from? I haven’t been able to verify that in my research.

  3. Lisa Reply

    I learned that you can have blood and urine tests on melatonin. I don’t know if they work, but I’m checking into it.

  4. Scott Reply

    I would appreciate guidelines on the best times to take it. E.g. I have woken up far too early this morning; is it a good idea to take some in order to try to get back to sleep?

  5. Beverly Bortin Reply

    If I take melatonin regularly will it inhabit the normal production of melatonin in my body. If so, does that mean that I should not take it every night on a regular basis?

  6. Emery 4 Reply

    I have been talking 2 10g of melatonin for sleep is that safe

  7. Trish Reply

    Melatonin works for adults. I would be nervous to try it with children though. I would definately talk to a doctor first before putting a kid on some new medication even if it is over the counter.

  8. Jeff B Reply

    Also, I almost forgot…
    I read that there is much research on melatonin. I was just wondering if they are sponsored by melatonin companies or if they are independent research without bias.

    • Ceci Post authorReply

      Obviously, you are going to get more unbiased data from university studies that are govt funded and not funded by melatonin supplement manufacturers.

  9. Jeff B Reply

    I have tried melatonin a few times before with mixed results. For the most part, I did not feel any side effects. What does are you guys taking? Do you need to take it long term to notice the results of melatonin?

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