Biological Clock: How Does It Work?

Intuitively, everyone knows what the biological clock is. Each person feels the presence of that internal timer that tells them what time to sleep and what time to wake up and that determines different physiological changes throughout the day.

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

Today it is not only known how the biological clock works, but it has also been established that alterations in it are a risk factor for the development of many diseases. Life on Earth is also known to move in time with these natural cycles.

What is a biological clock?

In general terms, the biological clock is an internal mechanism of living beings that allows them to orient themselves temporarily. What it does, in a basic way, is to organize in time various organic activities such as sleeping, eating, etc.

The biological clock, like the conventional clock, works in cycles. This means that it develops continuous sequences that complete and start all over again. That is the reason why, from time to time, we feel hungry or sleepy again, for example.

This clock is related to functions such as sleep regulation, hormone release, eating behavior, and even blood pressure and body temperature. Scientists say it is a kind of ‘molecular script’ that all living organisms possess.

The background to the discovery

All life on Earth works in a coordinated way with the rotation of the planet. Day and night are the basic parameters around which living beings move. Since the 18th century, the astronomer Jean Jacques d’Ortous de Mairan noted that there were functions in plants that were performed during the day and others at night, regardless of whether they were exposed to light or not.

In the 1960s, the biologist Franz Halberg spoke of circadian rhythms for the first time to refer to those biological processes that took place 24 hours a day. These were basically sleeping at night and being awake during the day. However, it was not known what caused these cycles.

Geneticist Seymour Benzer and his disciple Ronald Konopka studied the possibility that the biological clock mechanism was activated by genes. However, it was only until 1984 that researchers Jeffrey Hall, Michael Rosbash, and Michael Young managed to identify the genes and then discovered how the whole mechanism worked.

How does the biological clock work?

The biological clock is a dance of genes in which, to understand it simply, two of them predominate during the day, while another two prevail at night. Its action is complemented by at least ten other genes. Between all they regulate the diurnal and nocturnal processes of the organism.

The mechanism of action is as follows:

• At the beginning of the day, the clock and cycle genes begin to be activated and the proteins they produce accumulate throughout the day.
• When there is a large accumulation of such proteins, towards the beginning of the night, other genes called period and time are activated.
• Throughout the night, the proteins generated by the period and time genes accumulate. This inhibits clock and cycle production.
• As the proteins of the clock and cycle genes decrease , the period and time genes are deactivated, which require the accumulation of the former to be activated.

Data to take into account

An organism works better and remains more stable if it works at the correct rate of the biological clock. This essentially means sleeping the right number of hours at night and being active during the day, eating at the most convenient times.

This internal timer works both in each cell and in each organ of the body of living beings. The way in which that clock works in each individual determines a certain tendency to be more productive at certain times.

Likewise, the body’s response to external stimuli changes, depending on the time. It is known, for example, that the body reacts differently to a drug whether it is taken during the day, in the afternoon or at night. This field is known as ‘chronopharmacology’.