How Exactly Does the Biological Clock Work?

The biological clock is a kind of body timer that "tells" the body when to perform certain physiological functions, such as eating or sleeping. Failure to synchronize with it often leads to sleep disorders and certain diseases.
How Exactly Does the Biological Clock Work?

Last update: 09 September, 2021

We all intuitively know our biological clock and feel its presence. This is because it’s a sort of internal chronometer that tells us it’s time to sleep or wake up. Furthermore, it determines the various physiological changes we experience throughout the day.

The concept of a biological clock as such is familiar to many, although the discovery of how it works is relatively recent. It was the scientists Jeffrey C. Hall, Michael Rosbash, and Michael W. Young, winners of the 2017 Nobel Prize in Physiology or Medicine, who unraveled that mystery.

Not only do we currently know how the biological clock works, but we established that its alterations are a risk factor for the development of many diseases. We also know that life on Earth moves to the rhythm of these natural cycles.

What’s the biological clock?

A person adjusting a clock.

In general terms, the biological clock is an internal mechanism of living beings that allows us to temporally situate ourselves. What it basically does is give instructions to the various organic activities — such as sleeping, eating, etc. when we have to.

Just like a conventional clock, the biological one works in cycles. This means it develops continuous sequences that fulfill their cycles and then start over. This is why we feel hungry or sleepy again from time to time, for example.

This clock regulates functions such as sleep, hormone release, eating behavior, and even blood pressure and body temperature. Scientists say it’s a kind of molecular script all living organisms possess.

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Some background

All life on Earth functions in coordination with the planet’s rotation. Thus, day and night are the basic parameters around which living things move. As early as the 18th century, the astronomer Jean Jacques d’Ortous de Mairan noticed that some functions in plants took place during the day and others at night — regardless of them being exposed to light.

In the 1960s, the biologist Franz Halberg first spoke of circadian rhythms to refer to the biological processes that take place during the 24 hour period every day. These were basically sleeping at night and remaining awake during the day. However, they still didn’t know what caused these cycles.

Geneticist Seymour Benzer and his colleague Ronald Konopka studied the possibility that genes activated the biological clock mechanism. However, it wasn’t until 1984 that researchers Jeffrey Hall, Michael Rosbash, and Michael Young succeeded in identifying the genes. It was then when they discovered how the whole mechanism worked.

How does the biological clock function?

An illustration about time.

The biological clock is a mixture of genes in which, to put it simply, two of them predominate during the day, while two others prevail at night. At least ten other genes complement their action and regulate the diurnal and nocturnal processes of a given organism.

The mechanism of action is as follows:

  • The clock and cycle genes begin to activate and the proteins they produce accumulate throughout the day at the beginning of the day
  • Other genes called period and time activate when there’s a large accumulation of such proteins, towards the beginning of the night
  • The proteins generated by the period and time genes accumulate throughout the night, which inhibits both the production of the clock and the cycle

A decrease in the proteins of the clock and cycle genes deactivate the period and time genes. This is because these need a protein accumulation to activate.

Facts to keep in mind

A body functions better and remains more stable if it works at the accurate rhythm of the biological clock. This essentially means sleeping the right number of hours at night and being active during the day, as well as eating at the best times.

That internal timer works in every cell, as well as in every organ of the body of living beings. The way this clock works in each individual determines a certain tendency to be more productive at certain hours.

Likewise, the organism’s response to external stimuli changes depends on time. Thanks to the field of chrono-pharmacology, we know the body reacts differently to a drug if you take it during the day, afternoon, or at night, for example.

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