A study of nearly 2,000 women found that those with mostly healthy sleep patterns before the pandemic had a significantly lower risk of developing long COVID than their poorer-sleep counterparts.

Interview by Alyx Arnett

Poor sleep commonly has been thought to increase one’s susceptibility to viruses like the common cold, and it more recently has been linked to an increased risk of COVID-19 infection. 

Whether sleep quality and duration affect the risk of developing long COVID, however, remained to be studied—until now. 

In a prospective cohort study of 1,979 women who reported testing positive for SARS-CoV-2 infection, Siwen Wang, MD, and co-investigators sought to determine the association of multiple healthy sleep dimensions with long COVID, a condition characterized by symptoms and conditions that are present four weeks or more after the initial phase of infection. 

Researchers found that women who had a pre-pandemic sleep score of 5 (mostly healthy) had a 30% lower risk of developing long COVID compared to women with sleep scores of 0 to 1, suggesting that healthy sleep efficiency and duration could reduce the number of long COVID cases or improve symptoms of the condition. 

Wang, a research fellow in the department of nutrition at Harvard T.H. Chan School of Public Health, discussed the study with Sleep Review over email. 

[Editor’s Note: Read the full study, Multidimensional Sleep Health Prior to SARS-CoV-2 Infection and Risk of Post-COVID-19 Condition, in Jama Network Open.]

What led you to investigate the relationship between sleep and long COVID?

It has been estimated that 8 to 23 million Americans suffer from long COVID, and around one in three people worldwide have sleep problems. Most of the currently known risk aspects for long COVID are demographic, such as sex, race, or income level, or illnesses, such as diabetes and hypertension. Therefore, we would like to investigate potential modifiable risk aspects for long COVID.

What were the key findings of your study regarding the association between sleep health and the risk of developing long COVID?

We found that people who followed most aspects of healthy sleep before COVID infection, including being a morning person, seven to eight hours of sleep per day, falling and staying asleep easily, no snoring, and no frequent daytime sleepiness, had about 30% lower risk of long COVID compared to people who did not have any of these aspects of healthy sleep.

Among these healthy sleep components, the ones most strongly associated with lower risk of long COVID were having enough sleep every day and good sleep quality. Chronic diseases, such as asthma and heart diseases, or hospitalization due to COVID-19 did not explain these findings.

What was the most surprising finding from your study? 

We were surprised that the associations between healthy sleep and long COVID remained strong after accounting for a wide range of preexisting medical conditions as well as severity of COVID-19 infection.

How do the findings contribute to the existing understanding of the relationship between sleep and long COVID?

Previous studies have suggested that unhealthy sleep is associated with higher risk of getting COVID-19 and more severe COVID-19 among those who were infected. Our findings suggest that healthy sleep before and during the pandemic, prior to infection, was associated with a reduced risk of long COVID.

What are the clinical implications of your research? 

Our study raises the possibility that simple steps—such as setting a regular bedtime; shutting off screens and removing electronic devices before bedtime; and avoiding caffeine, large meals, and alcohol late in the day—to improve sleep hygiene may reduce the risk of long COVID.

What further research should be done?

Further research should investigate whether interventions to promote healthy sleep help prevent or treat long COVID. Identification and treatment of biological pathways linking sleep with long COVID symptoms may benefit people with long COVID or, possibly, other chronic post-infection syndromes.

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