What Is Circadian Rhythm, Body's Master Clock That Hates Poor Lifestyle Choices

Circadian rhythm is a 24-hour cycle that runs in the background that regulates our sleep-wake cycle

Shubhangi Shah
Written by: Shubhangi ShahUpdated at: Sep 01, 2021 11:09 IST
What Is Circadian Rhythm, Body's Master Clock That Hates Poor Lifestyle Choices

Clocks and watches are some things humans made to make their lives easier. To tell them it’s time to sleep, wake up, eat and work. What if we tell you your body already has a clock, which does all these things, thanks to evolution. Circadian rhythm is our biological clock that does pretty much everything that a man-made clock does. But just as we press the snooze button on our alarm clocks, we turn off, or rather disrupt, this master clock by our poor lifestyle choices for which we pay a price with our health. 

To know more about the circadian rhythm and its impact on health, Onlymyhealth spoke to Dr Sudipto Chatterjee, a psychiatrist associated with Parivartan Trust, which deals with mental health and de-addiction. He described circadian rhythm as an “evolutionary response”, a 24-hour clock that runs in the background that functions, primarily, to the effect of day and night. Light is the primary stimulus, which is why we sleep in the night and stay awake during the day.

Circadian Rhythm: What Is It?

For circadian rhythm, light is the primary stimulus

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Have you ever wondered why we sleep and eat at a certain time, and if there is a deviation from that timetable, it impacts our mood? It is because of the circadian rhythm that regulates all these functions. It, in turn, is controlled by a region of the brain, called the hypothalamus, which also controls other vital functions such as body temperature, appetite, sexual behaviour, emotional response, among others. And it is not just the brain, but every cell of our body has an in-built clock. 

Wondering what is the best time to work? It’s around 7 am to 6 pm, a 10 to 11-hour window, when our brain is the most active, Dr Chatterjee said. As the light fades in the evening, our brain releases a hormone, called melatonin, which gradually reduces brain activity and we fall asleep. When light falls on our eyes, it sends signals to the brain that it is daytime, melatonin level decreases and we get alert.

Although the primary stimulus, light isn’t the only factor, which affects the circadian rhythm. Food is another factor, which is why we are told not to eat late at night. Even exercise has an impact as working out at the wrong hour can mess up with the rhythm. Also, avoid stimulants such as tea and coffee late in the evening as it affects the sleep cycle. The circadian rhythm doesn’t remain the same throughout our lives and is impacted by age, Dr Chatterjee said. That is why younger kids sleep more, teenagers sleep late, and the elderly sleep and wake up early. 

What If The Circadian Rhythm Gets Disturbed?

You feel tired and sleepy when your circadian rhythm gets disturbed

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A good example of a disturbed circadian rhythm is jetlag. Also, shift workers have the same disrupted, so do those working in the IT sector, who are often exposed to the bright blue light coming out of the computer screens late at night. It feeds the brain with the wrong signal that it is still bright outside, so there is no need to unwind.

Such people feel tired, sleepy at the wrong time, have low energy and have poor concentration. They are also prone to physical and mental health issues such as blood pressure, weight gain, sleep apnea and insomnia. Basically, “the more we deviate from our biologically-preferred lifestyle, the more the problems are,” the doctor said. We often talk about how lifestyle affects our health, the circadian rhythm is a very clear explanation of why that happens, he added.

Also read: Foods To Have And Avoid For A Good Night’s Sleep States Expert

‘How To Get Your Circadian Rhythm Back?

First and foremost, define what your normal functioning is -- when do you want to go to sleep and wake up, Dr Chatterjee said. Secondly, make adjustments for that. Have food at least two hours before going to bed, do not use your phone late at night and dim your bedroom lights. Also, it’s crucial to understand that it is a gradual process. If you currently go to bed at 1 am and want to sleep by 11 pm, first set 12 am as your goal and then reducing it to 11.30 pm and finally to 11 pm.

Also read: 5 Bedtime Teas That Can Help You Sleep Peacefully Through The Night

One of the questions we asked Dr Chatterjee was although a disturbed circadian rhythm has health impacts, does getting it back can cure diseases. “We don’t know for sure,” he replied. Having a proper sleep cycle has a positive impact on our mood, which in turn could be beneficial in cases of depression, insomnia and blood pressure. However, presently, there is insufficient research on if this can cure any diseases. However, it surely contributes towards it. So, next time, listen to your body and its internal clock, it might tell you more about yourself than you would imagine.

(With inputs from Dr Sudipto Chatterjee, a psychiatrist associated with Parivartan Trust)

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