Lack of sleep, insomnia, and daily burnout are being linked to a higher risk of becoming infected with COVID-19, suffering from more severe illness, and taking longer to recover, according to an international study of healthcare workers.

The findings show that every extra hour of sleep is associated with 12% lower odds of coming down with the disease, according to the BMJ Nutrition Prevention & Health online journal.

The researchers pointed out disrupted or insufficient sleep, as well as work burnout, have been linked to a higher risk of viral and bacterial infections, but it is not clear if those are also risk factors for COVID-19.

To explore further, they used responses to an online survey for healthcare workers who are repeatedly exposed to COVID-19 patients, putting them at higher risk of becoming infected.

The survey included healthcare workers in France, Germany, Italy, Spain, the United Kingdom, and the United States and was conducted in 2020 between July 17 and Sept. 25.

According to the report:

• 1 in 4 of those with COVID-19 reported difficulties sleeping at night compared with around 1 in 5 of those without it.
• 1 in 20 with COVID-19 said they had three or more sleep problems, including difficulties falling asleep, staying asleep, or needing to use sleeping pills on three or more nights of the week, compared with 3% of those without the infection.
• 5.5% of those with COVID-19 reported daily burnout than those without the infection, at 3%.

The survey asked respondents for details on lifestyle, use of prescription medicines, dietary supplements, and information about the amount of sleep they got at night and in daytime naps. They also reported if they had any sleep problems, were burned out from work, and had exposure in the workplace to COVID-19.

Out of the 2884 healthcare workers responding, 568 had COVID-19, and in the survey, infection severity was defined as ranging from very mild to critical, including respiratory failure requiring intensive care.

The respondents reported average nightly sleep as being under 7 hours and more than 6 hours, and after accounting for factors that were potentially influential, every extra hour sleeping was linked to having 12% lower odds of infection, and an extra hour of napping was linked with 6% higher odds.

The researchers acknowledged there were several limitations to their study, including subjective assessment of exposure levels, the severity of infection, and sleep issues, and the sample included only cases of very mild to moderately severe illness, reports BMJ.

The researchers also point out studies that link burnout to the risk of colds and flu and to long-term conditions like diabetes and cardiovascular disease.

"We found that lack of sleep at night, severe sleep problems and high level of burnout may be risk factors for COVID-19 in frontline [healthcare workers]," the researchers concluded. "Our results highlight the importance of healthcare professionals' well-being during the pandemic."

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