The Hormone of Darkness: Melatonin

by | Aug 31, 2021 | Anxiety, Depression, Men's Health, Women's Health

In a sea of over-the-counter sleep solutions, there is one product that seems to be marketed as the supreme option for natural sleep support and that is melatonin.

But what exactly is it?

It is commonly referred to as “the hormone of darkness” and this is simply because that is when it is released by the pineal gland – a small area in the back of the brain. Melatonin’s release begins soon after dusk, as the light input becomes less and less. Once it is released, it acts as a signal to the brain and body that it is dark outside and therefore time for sleep. So, it is actually acting as a regulator for the timing of sleep and has nothing to do with the generation of sleep itself. This is one reason why it is not a particularly powerful sleep aid in terms of keeping you asleep.  

Sunlight essentially acts as “the brakes” to melatonin release.

After you fall asleep, your amount of circulating melatonin slowly decreases (peaking at around 4am) until you are exposed to light, which begins a process of new signals to the brain that shut off melatonin release. Sunlight essentially acts as “the brakes” to melatonin release.

Once there is no more circulating melatonin, the brain knows that it is time to alert the body for wakefulness. This is also why, in a world full of bright screens, lights, and constant electronic use, many people are having disruptions in their ability to produce enough melatonin to signal sleep initiation and then support it throughout the night. 

Melatonin also helps to signal regulation of one of the hormones that inhibits appetite (leptin) and lowering of body temperature – all of which play different roles in sleep quality. 

How should melatonin be used?

The best uses of melatonin are for those:

  • who suffer from jet lag or shift work 
  • who’s natural melatonin levels may have lessened, such as the elderly 
  • who have been tested to have low melatonin

Accurate melatonin testing is not easily accessible to all and an easier alternative is to simply try and see if it is something that works for you. It should be noted that there is a significant placebo effect associated with it, which there is nothing wrong with (if it works, it works!), but this may be one reason why many find it loses efficacy rather quickly. 

A general dosing rule is to not exceed 3mg. Doses higher than this are unlikely to have additional benefits but do have higher potential for disturbing your body’s natural melatonin production. Although there is low risk of side effects with taking it, there is possibility that taking too much can affect your own ability to produce melatonin, making you more susceptible to depending on supplementation long-term.

As far as timing goes, it is best to take it before bed and at least 2 hours after your last meal. Eating while melatonin is in circulation is connected to higher levels of glucose and insulin. If eating at night is a regular habit, levels of glucose and insulin can remain elevated over time contributing to the development of type 2 diabetes.

It is also important to note that many forms of melatonin available over the counter are not regulated by any overseeing bodies for quality assurance. Some evaluations of available products have found concentrations that range from 83% less than what was stated to 478% above what was stated. So, it is important to buy from brands that are participating in quality control measures or ask your doctor for a recommended brand.

Despite this, it is a generally safe supplement with minimal side effects. Unwanted effects that are most commonly reported include headaches, morning grogginess, vivid dreams, and some digestive upset.

What affects melatonin production?

A better solution than supplementing with melatonin is knowing which things affect its production and release and making lifestyle changes around those things so that our bodies are better able to produce this on their own.

We know that light acts as the “brakes” to circulating melatonin. Therefore, it is important to diminish/eliminate external sources of light once the sun goes down. It is particularly important to eliminate the use of blue light during the dark hours of the evening. Many blue light-emitting devices include most electronics such as phones, TVs, computers, and tablets. It is best to try and find evening wind-down activities that do not involve the use of electronics (e.g reading, drawing, playing board games, listening to music).

Making sure the sleeping environment is as dark as possible is also important so that circulating melatonin is not affected during the night. A general rule is that, if it is bright enough to see your hand in front of your face, it is bright enough to put the brakes on your melatonin. Our skin also has light receptors, so a sleeping mask is not always enough to remedy this. Light-blocking curtains are best if outside light makes total darkness impossible.

Who should avoid it?

Main populations that should avoid the use of melatonin include children, those that are breastfeeding, and those who are pregnant or planning to become pregnant. Children are unlikely to have a melatonin deficiency, and unless it is being used for jet lag, it should not be a first choice as a sleep aid. There is potential for melatonin to effect reproductive hormones, which is why it is not recommended when breastfeeding, pregnant, or trying to become pregnant – regardless of which set of reproductive organs you possess. This is another reason it is advised against in children, as it is unknown the effect it may have on puberty.

Bottom line: This should not be anyone’s go-to as a long-term support of sleep, but rather something that is used strategically to alter sleep signaling. It is more important to promote the body’s own ability to produce melatonin and to minimize outside sleep disruptors.


  1. Walker, M., 2017. Why We Sleep: Unlocking the Power of Sleep and Dreams. 1st ed. New York: Scribner.
  2. The Truth About Melatonin: 6 Most Common Questions Answered. SleepScore. Published 2019. 
  3. Neubauer D. Melatonin: The Dark Side of the Hormone. Psychiatric Times. Published 2020.
  4. Darley C. Promoting Healthy Sleep. Presentation presented: 2019; National University of Natural Medicine, Portland, OR.
  5. Buscemi N, Vandermeer B, Hooton N et al. The efficacy and safety of exogenous melatonin for primary sleep disorders a meta-analysis. J Gen Intern Med. 2005;20(12):1151-1158.
  6. Image Source:


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