What is Melatonin?

What is Melatonin?

For anyone familiar with melatonin, this hormone is a household name mainly for its role in sleep improvement. However, melatonin’s recognition for sleep enhancement alone paints an unfair, or at least incomplete picture of its important functions for daily life.

Melatonin is your body’s master-clock. Without even knowing it, this hormone keeps you aware of the time of day, and season of the year you’re living through. This hormone regulates the sleep-wake rhythm, hormone-release rhythm, and even your body temperature to a certain extent. Melatonin also influences nearly every tissue you’ll find in your brain and body. 

Early in life, this hormone is suspected to be involved with fetal development. It also regulates the fetus’ internal clock while in the belly. The ‘sleep supplement’ may even impact protection for the brain, and how the nervous system develops. But that’s not all, melatonin is also a key player in blood pressure, kidney function, and immune system regulation¹.

Given the many important roles played by this hormone, it’s a bit of a downgrade to use it only for well—sleep improvement. This is especially because a close look at melatonin’s physiological functions will show that sleep is a mere side-effect produced when it guides the sleep-awake rhythm. With all these functions to perform, let’s delve a little deeper into the natural biochemistry of melatonin to understand how it manages it all. 

Melatonin is produced from the essential amino acid, tryptophan. You’ll find this amino acid in everyday protein. In particular—fish, meat, cheese, and dairy products are rich in tryptophan. In the first step, this amino acid is hydroxylated to 5-Hydroxytryptophan, and then carboxylated to serotonin, the ‘feel good’ neurotransmitter. 

Serotonin is acetylated and then methylated to form melatonin. The acetylation is catalyzed by a complicated-sounding enzyme we don´t have to remember. What’s more important is this enzyme’s nickname—“timezyme”. To regulate our inner clock, timezyne creates melatonin. Timezyne is tightly regulated because it is hard-pressed to produce exactly the amount of melatonin you need for daily life. 

Naturally, to keep you alert, the melatonin concentration in blood is very low during the day (between 10-15pg/ml) and starts to rise around 10 p.m. in the evening. Your body will have its highest peak of melatonin early in the day between 2-4 a.m., rising to 120pg/ml. After this, the concentration declines again because melatonin is degraded. 

Put simply, you need to recall at least two things from this short deep-dive into biochemistry: 

  1. Tryptophan is the precursor for serotonin (good mood) and melatonin (sleep)
  2. Melatonin cannot be converted back to serotonin

Now, if you take melatonin as a supplement (normal dosing is 1-5mg), you kick the melatonin concentration in your blood up to 12ng/ml. That is 100 times your natural peak level and 1000 times your natural level at this moment in time during the night. At this level, you are immediately lulled to sleep. Melatonin at that concentration promotes resting in the early hours of your night. 

But while you enjoy a good night’s rest, this can come at a cost. Melatonin supplements carry out the natural functions of the hormone. This means other areas, critical to the melatonin function like your natural sleep-wake rhythm—may be affected. 

This double-edged sword is a bit disappointing because melatonin is a great tool for influencing sleep. How can we get it to influence rest alone, without risking other processes that work well in our body and brain?

Let's have a look at the biochemistry again. Apparently, the safer and more efficient approach is to focus on the starting point of melatonin synthesis: tryptophan. With enough tryptophan in your diet, your brain can naturally decide how much melatonin is required and when. 

If you remember, tryptophan is also the starting material for serotonin on its way to melatonin. When you use tryptophan, you’ll get a good mood (serotonin) and enough sleep (melatonin) in the right amounts. 

This sounds magical, but it is just the natural way our brain is built. It’s also the right balance of what we need for daily life—positivity and the right energy to perform during the day.

In conclusion, your natural systems work just fine with minimal interference. Unless you absolutely have to, it’s probably best to let your brain and body operate as they are designed.


¹  Grivas TB, Savvidou OD. Melatonin the "light of night" in human biology and adolescent idiopathic scoliosis. Scoliosis. 2007;2:6. Published 2007 Apr 4. doi:10.1186/1748-7161-2-6