We all know the importance of a good night’s sleep. What not everyone knows is that the alternating between sleep and being awake is the result of the combined action of various chemicals in our brain.

And among the most important are melatonin and adenosine, two substances with a very active role in sleep regulation.

Adenosine is a byproduct of energy consumption by the body. Scientists think that it accumulates in the body throughout the day, generating a feeling of tiredness and sleepiness which marks the beginning of the sleep process and is then removed while we sleep, to wake up fresh as a daisy! That’s why we fall asleep easily after a tiring day and feel tired when we don’t get enough sleep!

One of the strongest evidences of the role of adenosine in sleep is its competition with caffeine. Caffeine binds to the same brain receptors as adenosine, preventing it from acting, which explains why caffeine can prevent us from falling asleep. Imagine that we put chewing gum in a lock whose key is adenosine; we manage to open the door, but only after a few hours cleaning the lock.

Melatonin, in turn, is a hormone produced by the pineal gland, a structure within the brain. The presence of melatonin in the brain inhibits the alertness and contributes to sleep.

The production of melatonin is extremely sensitive to light: it is stimulated by the approach of night, but it’s inhibited as soon as the retina detects light. The smallest amount of light reduces the production of melatonin, which is why we begin to wake up when the sun rises, or because there are people who can only sleep in complete darkness.

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