Melatonin Mechanism of Action

Instructor: Justine Fritzel

Justine has been a Registered Nurse for 10 years and has a Bachelor's of Science in Nursing degree.

Melatonin is a supplement that can help with insomnia without side effects like sleeping pills have. In this lesson we will learn about how melatonin works.


You may recognize the term melatonin as a medication to help with sleep and you are correct. Did you also realize melatonin is a hormone naturally produced in your body to regulate your sleep/wake cycle? It is! It is produced by the pineal gland in your brain related to the light/dark cycle.

As it becomes dark, melatonin is produced which causes you to become tired and lowers your body temperature so you can prepare to sleep. Although we all produce this hormone, there are many people that still have trouble sleeping so melatonin is available as a supplement to take to help with insomnia.


Let's look closer at the brain to help us understand how melatonin helps us to sleep!

Understanding the Brain

The brain is the control center of all of our body functions. There are different parts of the brain that control different functions. Deep in the center of your brain is the hypothalamus. The hypothalamus produces many of the hormones for our body and regulates many biological functions, one of which is sleep.


Within the hypothalamus is the suprachiasmatic nucleus (SCN). This is believed to regulate your circadian rhythm. Within the SCN are receptors which are nerve endings that receive stimuli to tell them to do something.

Our body is a fine oiled machine. The most complicated, amazing machine in existence! There are many different pieces working together to keep the machine working.

Now that we have a basic understanding of some of the ways our brain works, let's look closer at how melatonin works to help us sleep.

Mechanism of Action

When you take melatonin, it binds to two receptors within the SCN of the hypothalamus. Specifically, it acts on melatonin receptor 1, MT(1) and melatonin receptor 2, MT(2). When melatonin binds to MT(1) and MT(2), it sends signals to other receptors that start a cascade of actions ultimately resulting in the effects of melatonin.

Remember the dominoes game? You set up your whole row of dominoes and you tap your finger on that first domino to start the whole row of dominoes falling. Melatonin binding to MT(1) and MT(2) is that first domino. Taking melatonin is the same as tapping that first domino, it starts the whole process to obtain the desired effects.

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