Opinion: How your body clock helps determine whether you’ll get ill or not

From vitamin C and echinacea to warm clothes and antibacterial soap, there’s no shortage of ideas about how to prevent and manage colds and flu. Unfortunately, many of these are not based on solid scientific evidence. In fact, medical researchers are only starting to unravel the range of factors that affect our susceptibility to getting an infection. Now we have discovered that our body clock plays an important role – making us more prone to get infected at certain times of the day.

It is perhaps easy to forget that we have co-evolved on this planet with micro-organisms, including bacteria, which may be either beneficial or harmful to us. Similarly, viruses cannot copy themselves without help from our cells. Without us, they simply wouldn’t exist.

So what happens when a virus encounters a cell? First, it has to get in through a protective barrier called the cell membrane. Then it has to hijack the interior of the “host” cell to subvert it and divert all resources to copy itself millions of times. Once an army of identical clones is formed, it breaks out of the cell, usually destroying it in the process. Imagine millions of these new viruses then being able to do exactly the same to other cells nearby. The cycle goes on, with often rapid amplification of the virus through a tissue, and then through the body.

That’s if the virus had it all its own way … But there is always a battle in play between invading organisms and our bodies. Our immune system counteracts the invading organisms and will invoke mechanisms to stop the virus entering, replicating and spreading. This defence system works at the level of individual cells in the body, but also in specialised tissues of the body that are designed to mount a response to such invasions.

It now turns out that our body clock is also an important gatekeeper of virus infections. The body clock is an amazing piece of evolutionary biology. It’s thought that most organisms on our planet have a biological clock that keeps track of the 24-hour day. It can do this by orchestrating chemical reactions and genetic switches that rhythmically control thousands of genes in cells in the cell – turning about 15% of all genes on and off across the day and night.

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Image: Sick
Credit: Claus Rebler


Reproduced courtesy of the University of Cambridge
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