The Heart of Time

According to the earth's rotation, it is now early in the morning. The golden sun has just begun to shine. The early rays of the sun squeeze in through the curtains. The rays enter your eyes and hit the retina within them, immediately firing a series of electrical signals to the brain. In turn, the brain now stops producing melatonin, the sleep-inducing hormone. The blood pressure rises, the pulse races again. You wake up. You are ready to face the world. Interestingly, your body has begun to prepare itself for waking even before dawn.

The rays of the sun are only the final confirmation of the start of your day. Inside our brain, there is a control centre, also called the biological clock. This clock, with inputs from the rays of the light received by the eye, decides when we sleep and when we wake up. The Nobel Prize in Physiology or Medicine 2017 was jointly awarded to three scientists for their work in decoding this biological clock. A timely award, because the function and malfunction of the biological clock has been linked to several diseases, including heart disease, Diabetes and obesity.

Here are some instances of the effect of the biological clock on the heart: the human heart cells, by themselves, have been found to have an internal clock. The heart rate as well as the blood pressure – both change according to the time of day. A lag of a few hours in our sleep-wake cycle has been found to slightly increase the odds of a heart attack.

This lag could arise from trans-meridian flights, shift work or even social activities such as late night parties or binge eating in the night. Such disruptions, where our 'social clock' is different from the 'environmental clock', may also increase the risk of obesity and Diabetes. This study of the effect of time on the heart, called 'chrono-cardiology', is just beginning to unravel new therapies. In a sense, the heart tells our time. We live as long as our heart does. The day our heart stops beating, we cease to live too.

In addition to all the tips, here is a bit of an advice: keep your biological clock in mind. Eat on time, sleep on time and let your sleep-and-wake time be in sync with the rotation of the earth around the sun.

It seems I have spent my whole day pondering over all this. The golden sun has, by now, already slipped under the horizon. My sleep-inducing hormone levels are probably rising in the blood. My heart rate is dropping, the blood pressure is falling. Darkness has descended – a good thing, because I need to sleep, so that my brain can reboot and prepare for what lies ahead tomorrow.

Dr Unnikrishnan AG

Editor