Catching the Optimal Amount of Z's May Be Protective Against Long COVID

Healthy sleep behaviors before and during the pandemic may be protective against long COVID, a prospective cohort study suggested.

Of nearly 2,000 women from the Nurses' Health Study II who tested positive for SARS-CoV-2 infection, those with the most healthy prepandemic sleep score had a 30% lower risk of developing long COVID compared with those who had the least healthy scores (multivariable-adjusted relative risk 0.70, 95% CI 0.52-0.94, P<0.001 for trend), reported Siwen Wang, MD, of the Harvard T. H. Chan School of Public Health in Boston, and co-authors.

No or little daytime dysfunction before the pandemic and good sleep quality during the pandemic were independently associated with a lower risk of long COVID (relative risk 0.83, 95% CI 0.71-0.98 and relative risk 0.82, 95% CI 0.69-0.99, respectively), they noted in JAMA Network Open.

These associations did not differ based on healthcare worker status -- whether participants provided frontline care or not, Wang and team said.

"We already know that healthy sleep is good for overall health," Wang told MedPage Today, adding that previous studies have also linked poor sleep with increased risk of COVID-19 infection.

"Our findings further suggest that healthy sleep is not just beneficial for the prevention of chronic diseases, but also helps with your immune system," she said.

While the researchers did not study the biological pathways that may be driving the relationship between sleep and long COVID, all of the examined sleep dimensions have been tied to "systemic inflammation and immune aberrations," they noted.

Wang said that both inflammation and immune dysregulation have been associated with a higher risk of persistent COVID symptoms. "There's also evidence showing that people with unhealthy sleep aspects sometimes have gut microbiome changes or blood clotting disorders that have also been associated with higher risk of long COVID," she added.

In their study, Wang and team wrote that "the proinflammatory state may predispose those with poor sleep health to the occurrence of cytokine storms, which have been proposed to be involved in the multiorgan manifestations of PCC [post-COVID-19 condition]."

More studies are needed to understand the precise ways in which healthy sleep could reduce the risk of long COVID, Wang said, noting that she hopes future studies will also explore whether improving sleep may help relieve symptoms of long COVID. Simple steps to improve sleep hygiene could include setting a regular bedtime, shutting down screens and removing electronic devices, and avoiding large meals late in the day.

For this study, Wang and co-authors used survey data from the Nurses' Health Study II. Among the 1,979 participants reporting SARS-CoV-2 infection, mean age was 64.7, and 97.2% were white. About 43% were frontline healthcare workers, and 44% developed long COVID.

Sleep health was measured from June 2015 through May 2017. The prepandemic sleep score -- 0-1 indicated the least healthy sleep, and 5 indicated the most healthy sleep -- was defined according to five dimensions: morning chronotype (being a so-called "morning person"), sleeping 7 to 8 hours each night, low insomnia symptoms, no self-reported snoring, and no frequent daytime dysfunction, including difficulty with fatigue, mood, concentration, or memory.

In the first COVID-19 substudy survey, which was returned between April and August 2020, participants were asked about average daily sleep duration and sleep quality for the past 7 days.

Sensitivity analyses showed that the association between poor sleep and long COVID was not "purely explained" by factors such as hospitalization for COVID and depression and anxiety, which could affect sleep quality, Wang noted.

One limitation of the study was that the participants were white, middle-age women, so the results may not be generalizable to other populations, the authors said. In addition, the study was conducted during the phase of the pandemic when the primary variants were Alpha and Delta, meaning the results may not apply to subsequent variants.

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