Getting enough sleep at night may help curb people’s risk for getting Covid-19, as well as for developing more severe illness, new research suggests.

The study included more than 2,800 frontline health care workers in six countries who were regularly exposed to Covid-19 from last spring to last autumn. It found that for each additional hour of sleep the workers got at night, their risk for Covid-19 dropped by 12%.

And those who said they were struggling with self-reported burnout had a higher risk of contracting the virus. They also tended to stay sick for a longer period of time and were more likely than those who said they weren’t burnt out to get seriously ill.

“Lack of sleep, severe sleep problems and burnout may be risk factors for Covid-19 in health care workers,” said Steven Holfinger, a sleep medicine expert at The Ohio State University Wexner Medical Center, who did not work on the new study.

Holfinger added that he thinks “further research to better define this risk would be helpful,” and cautioned against jumping to conclusions based on the new study, which was published recently in the journal BMJ Nutrition, Prevention, and Health.

For one, the study did not necessarily account for all the reasons why exhausted health care workers may be more likely to come down with Covid-19. For example, they might simply have been seeing more patients. Holinger also noted that the pandemic has evolved so much since last spring, particularly with the emergence of new variants, that the “data should be interpreted with caution” today.

Yet the new research is not the first to suggest there is a link between sleep and Covid-19 risk.

A small study out of China found that people who did not get much sleep in the week before they came down with Covid-19 appeared to have more severe outcomes. Researchers are also exploring the possibility that melatonin, the hormone that plays a crucial role in the sleep-wake cycle, may help stave off Covid-19.

Again, those investigations — and others — are not conclusive, and experts caution against over-interpretation. It is not as though regularly getting a good night’s rest is all that is needed to stave off Covid-19.

But sleep is an important factor in immune function.

“As our bodies fight infections we release cytokines which promote sleep, causing an increase in sleep during infections,” Holfinger said. “We presume that this is advantageous for our immune system to fight infections, so the current hypothesis is that sleep is beneficial to our immune health.”

And during a pandemic when so many factors determining individual Covid-19 risk are utterly outside of any one person’s control, it is tantalising to consider that there could be another health habit that many (though certainly not all) of us have some direct agency over. 

As writer James Hamblin, a board-certified physician specialising in public health, asked in a recent Atlantic article on the sleep and Covid-19 connection: “Is one of the most glaring omissions in public-health guidelines right now simply to tell people to get more sleep?”

Experts have coined a new term for coronavirus-era sleep issues: “coronasomnia” (also “Covid-somnia”). Prescriptions for sleep medications have jumped. People are grappling with significant chronic stress, and they are isolated. Emerging evidence also suggests that the virus itself hampers sleep among those who have recovered, particularly Covid-19 long-haulers. 

Of course, the primary means of preventing Covid-19 transmission remain the same as ever: masking, hand-washing, social distancing and widespread vaccination.

But to the extent people are able, they should also prioritise sleep. Even if ongoing investigations into the sleep and Covid-19 link do not demonstrate a linear connection, sleep is in many ways the bedrock of physical and mental health.

“It is very common for people to not allow themselves enough time in bed at night. People intentionally causing themselves to be sleep-deprived (staying up late watching TV, or getting up early to be productive) are therefore likely reducing their immune system’s response to infections,” Holfinger said. 

“Avoiding sleep deprivation will not only likely help their immune system, but also help with their overall quality of life.”