Like everyone else, I have been overwhelmed by the speed at which COVID-19 has emerged from nowhere and threatened our way of life. At the end of December, it was just a few ‘flu-like cases’ in Wuhan. Now it is a pandemic, which, for many people, has only just begun.


I’ve seen it up close, as two of my sons have had it. One of them, Daniel, returned in mid-March from Australia where he had been sharing a flat with two doctors. A few days later he got a call from one of his former flatmates saying he had tested positive for COVID-19, as had four other of their mutual medical friends.

The following day Dan got all the classic symptoms, including cough, fever, headache and loss of taste or smell. I’m glad to say that within a couple of days he was fine.

His older brother, Jack, who is a doctor working in a respiratory ward near Manchester, which was full of patients with COVID-19, also went down with the same symptoms. Like Dan, he was soon well again, though he has yet to recover his sense of smell.

Read more about the science of sleep:

I am 63 years old and male, which puts me into a much higher risk category. As well as washing my hands and isolating, one of my top priorities is getting a good night’s sleep. That’s because a good night’s sleep is vitally important for keeping your immune system in great shape. Numerous studies have shown a clear link between stress, poor sleep and vulnerability to viral infections.

We know that while you are in deep sleep your body makes and release cytokines, which are proteins that function as chemical messengers for regulating your innate and adaptive immune response.

Quality sleep is also important for the production of infection-fighting antibodies and cytotoxic T cells (also known as killer T cells). A recent study showed that the ability of killer T cells to bind to and destroy infected cells was reduced after a single night of poor sleep.

Those who slept less than six hours were four times more likely to get a cold © Kate Copeland
Those who slept less than six hours were four times more likely to get a cold © Jason Raish

The importance of getting a good night’s sleep in fighting off viral infections was highlighted by a fascinating study, carried out in 2015 by researchers from the Universities of California and Pittsburgh in the US.

For this study, 164 healthy men and women, aged 18 to 54, were recruited to wear sleep trackers for a couple of weeks, and researchers also kept a record of how well they slept. The volunteers were then brought into a lab and asked to inhale nasal droplets containing cold-inducing viruses.

The volunteers were kept isolated, in a nearby hotel for another five days to see if they got infected, as measured by the presence of the virus or a four-fold increase in an antibody response. And, if they were infected, did they develop symptoms?

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Of the 164 participants, 124 (75.6 per cent) became infected, and 48 (29.3 per cent) developed a biologically verified cold. One of the striking findings was that those who slept less than six hours a night were four times more likely to actually get a cold than those who got seven hours or more.

That’s a great reason to prioritise a good night’s kip.



Dr Michael Mosley is former medical doctor, health writer and BBC presenter. He’s best known as presenter of Trust Me I’m a Doctor on BBC Two but has also written a number of bestsellers about personal health and medicine, including The Fast Diet, Fast Asleep and Fast Exercise.