Your Body Clock & Sleep - How Are They Related?

Do you receive internal indications like, ‘time to sleep’ or ‘its morning, wake up!’? It’s none other than the body clock that ticks you with all these indications. It is also known as the circadian rhythm.

What is a circadian rhythm? 

Circadian rhythm is a natural internal clock that keeps on ticking 24 hours a day and regulates our sleep/wake cycle. This timekeeper is controlled by a tiny area of our brain called Suprachiasmatic Nucleus (or SCN). It is located in the hypothalamus, directly above the optic chiasm where the optic nerve fibers cross. This particular location enables the SCN to respond to the presence of light, which is why we feel most alert during the sun shines and get ready to sleep when it’s dark. Apart from the sleep/wake cycle, circadian rhythm controls body temperature, our immune system and other body functions (like hunger) also.

How is the circadian rhythm related to our sleep/wake cycle?

Getting into an exposure of light, the circadian rhythm of our body starts ticking and continues for 24 hours a day. To elaborate, responding to the presence of light, the suprachiasmatic nucleus (SCN) initiates signals to the other parts of the brain that control hormones. It results in the rise of body temperature and the release of hormones like cortisol and melatonin. 

Melatonin is the hormone that primarily makes us fall and stay asleep.

Melatonin – The Dracula of Hormones

Melatonin is a hormone naturally produced by the pineal gland of our body. During the day time or in the exposure of bright light, this gland remains inactive. When the sun sets or the environment is dark, the suprachiasmatic nucleus (SCN) wakes the pineal gland up to start producing melatonin and releasing it in the blood. The rise of melatonin in blood makes us less alert and feel sleepy. It stays elevated for almost half a day in our blood in the presence of darkness and gradually goes low when the sun goes up. That’s why, in the daytime, the melatonin level in our blood is almost undetectable.

A fun fact about melatonin – As its level rises in our blood only when it’s dark, Melatonin is often called as the ‘Dracula of Hormones’.

However, our body clock also sometimes fails to instruct the pineal gland to produce melatonin if we are present in a brightly lit environment. Apart from sunlight, artificial indoor lights also can prevent the pineal gland to produce and release melatonin. 



A few interesting facts about circadian rhythm:

Our circadian rhythm will change in the course of life, as you get older. 

We all have different sleep/wake cycles, yours one may not match with your partner’s, parents’ or children’s ones.

The more you become conscious about your sleep time, sleep hygiene, your feelings of alertness and drowsiness, developing good sleep habits, the better sleep you will get and the better you will feel.