How does melatonin promote sleep? Scientists look to worms for answers

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  • Melatonin promotes sleep in humans, yet it is not understood exactly how this happens
  • Sleep in worms is similar to sleep in humans
  • Scientist, therefore, used roundworms to reveal how melatonin works in the brain

Melatonin is a hormone produced in the brain that regulates our natural sleep-wake cycle, and it is produced in response to darkness.

It is also used as a dietary supplement to help treat conditions like delayed sleep-wake phase disorder (DSWPD) and jet lag. Until recently, it was not understood exactly how melatonin works in the human brain.

What was known is that in order to promote sleep, melatonin has to link with melatonin receptors in the brain. In the human brain, these two receptors are known as MT1 and MT2. Researchers, however, did not know exactly what happens once melatonin links with these receptors.

Do worms sleep?

Interestingly, worms do sleep, and researchers noted that sleep is quite similar in worms, humans and mice. Neuroscientists from the University of Connecticut School of Medicine used C. elegans worms (also known as roundworms) to study this phenomenon. 

The found that when melatonin binds with the MT1 receptor it opens a potassium channel, known as the BK channel, that is responsible for limiting the release of neurotransmitters.

No receptor means less sleep

Put simply, when neurotransmitter release is inhibited, sleep is promoted. However, in order for the BK channel to limit neurotransmitter release, a melatonin receptor is necessary.

As a result, the researchers found that melatonin promoted sleep in worms by stimulating the BK channel through the melatonin receptor. When worms did not produce melatonin, lacked melatonin receptors or the BK channel, they spent less time sleeping. 

How does this benefit humans?

Because sleep is similar in worms and humans, these findings helped researchers understand how melatonin works in the human brain – which may lead to ways to alleviate sleep-related conditions.  

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