December 2017 | Issue 33
The tick-tock of our body clock

Sean Firoz_Byline.jpgBy Sean Firoz, Senior Executive, Communications & External Relations

Have you ever wondered why we wake in the morning and sleep at night? What makes us feel so alive during the day but so tired at nightfall?

This routine of waking and sleeping is all down to our internal, biological clock. This clock - the circadian rhythm - helps our body anticipate and adapt to the regular rhythm of the day, synchronising us with the Earth’s revolutions. The inner workings of our biological clock were shrouded in mystery, until three scientists, Jeffrey C. Hall, Michael Rosbash and Michael W. Young, discovered what makes our biological clock tick.

The circadian rhythm is a 24-hour cycle that regulates the body’s physiological processes, governing our time to sleep, rise and eat. During the 18th century, French astronomer Jean-Jacques d’Ortous de Mairan recorded the first observation of the circadian rhythm, noting the 24-hour movement pattern of leaves from a mimosa plant. Mimosa leaves open during the daytime and close at dusk, much like how we rise and sleep. And when the plant was placed in total darkness, he found that the leaves of the mimosa continued to follow their normal daily oscillation, hinting at the existence of their own biological clock.

Delving deeper into the circadian rhythm, a study in the 1970s on fruit flies identified the gene that controls the circadian rhythm. American physicist Seymour Benzer and his student Ronald Konopka, who conducted the study, found that a mutation in the gene called period disrupted the circadian clock of the flies, causing them to have faulty internal clocks.

Following up on that study, Jeffrey Hall and Michael Rosbash from Brandeis University, US, succeeded in isolating the period gene, which led to the fascinating discovery of how PER, a protein encoded by period, accumulates during the night and degrades during the day. The PER protein oscillates over a 24-hour cycle, much like how the circadian rhythm functions in the human body.

With the discovery of the PER protein came another mind-boggling question: how does the PER protein produce and degrade like clockwork in the cell? In 1994, Michael Young at Rockefeller University discovered a second body clock gene known as TIM. When TIM proteins join with PER proteins in cells, they both stick together and travel into the nucleus, and shut the period gene down. This ultimately produces a 24-hour-long feedback loop. For their discoveries of the molecular mechanisms that control the circadian rhythm, the three scientists were awarded the 2017 Nobel Prize for Medicine or Physiology.

At a time when globe-trotting has become the norm and many jobs require shift work, our biological clock takes a big hit. Come night time, the body produces a hormone called melatonin, which helps us fall and stay asleep. Having to work late at night in artificial light or traveling to new time zones confuses the production of melatonin, making less of it at night instead of the ​day, which in turn affects the circadian rhythm and sleep patterns of people.

These disruptions to the rhythm of our internal clock increase the likelihood of getting disorders like bipolar disorder and major illnesses like cancer. That is why it is important for people to have proper sleep at night to be productive throughout the day.

The next time you’re thinking of bingeing the latest season of Orange is the New Black through the wee hours of the night, you might want to take a break and think of the detrimental effects that come from disrupting your body clock.