A recent study published in JAMA Network Open examined the relationship between multidimensional sleep health and post-coronavirus disease 2019 (COVID-19) condition (PCC).
Study: Multidimensional Sleep Health Prior to SARS-CoV-2 Infection and Risk of Post–COVID-19 Condition. Image Credit: vetre/Shutterstock.com
Background
PCC is defined as the persistence of COVID-19-related symptoms for over four weeks after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, affecting 20% to 70% of infected individuals. PCC encompasses diverse symptoms such as persistent cough, fatigue, brain fog, depression, and anosmia.
The etiology, prophylaxis, and treatment of PCC remain unknown. Sleep problems are common but overlooked risk factors.
COVID-19 has compounded the severity of pre-existing sleep disorders. Unhealthy sleep dimensions, such as daytime sleepiness, late chronotype, long or short sleep duration, sleep apnea, and snoring, have been associated with susceptibility to and severity and mortality of COVID-19.
These dimensions are linked to immune aberrations and low-grade chronic inflammation implicated in PCC pathogenesis. Notwithstanding, the association between pre-COVID-19 sleep health and the risk of PCC remains undefined.
About the study
In the present study, researchers prospectively examined the association between multiple dimensions of sleep health before and early in the COVID-19 pandemic and PCC risk.
Participants were identified from the Nurses' Health Study (NHS)-II, established in 1989. A COVID-19 sub-study was initiated in April 2020 among active participants of NHS-II, henceforth referred to as the baseline.
The team measured sleep health dimensions before (June 2015 – May 2017) and during the pandemic (April – August 2020). The five pre-pandemic sleep health dimensions were chronotype, snoring, insomnia, daytime dysfunction, and sleep duration.
Participants were queried about average daily sleep duration and quality in the past seven days at the COVID-19 sub-study baseline. Participants indicated SARS-CoV-2 infection, test date, and hospitalization.
Subjects were asked if they had COVID-19-related symptoms for more than four weeks in the final questionnaire, and those endorsing this question were deemed to have PCC and further asked to describe symptoms and their duration.
Anxiety and depressive symptoms were assessed at baseline. COVID-19 vaccination date was self-reported.
Poisson regression was used to calculate relative risks and 95% confidence intervals for the individual associations of sleep dimensions and scores with PCC risk.
Additionally, the team examined independent associations with PCC in a model mutually adjusted for all pre-pandemic sleep dimensions. Further, they investigated the joint association of sleep health before and during the pandemic with PCC risk.
Findings
The study included 1,979 females with a positive SARS-CoV-2 test, including 845 frontline healthcare workers. The average age of participants was 64.7, and most (97%) were White.
Participants with a healthier pre-pandemic sleep score were White, older, had lower body mass index (BMI), more likely to follow a healthier lifestyle, and less likely to have asthma, hypertension, and type 2 diabetes.
Frontline healthcare workers were more likely to be younger and less likely to have comorbid conditions than others. There was a moderate correlation between sleep dimensions. PCC symptoms were reported by 44% of participants.
A healthier pre-pandemic sleep score was associated with a lower PCC risk in a dose-response manner.
The association of sleep score with PCC was not different by healthcare worker status. Chronotype, daytime dysfunction, insomnia, and sleep duration before the pandemic were associated with the risk of PCC when adjusted for age and ethnicity/race. Sleep quality (in the early pandemic) was related to the risk of PCC.
Sleep duration of 6-10 hours or longer was not associated with lower PCC risk compared to five hours of sleep. Pre-pandemic daytime dysfunction and pandemic sleep quality exhibited the strongest associations.
Additional adjustment for health risk factors attenuated associations by up to 13%. The researchers observed an independent association of only daytime dysfunction with lower PCC risk when all pre-pandemic sleep dimensions were considered.
Participants with healthy sleep patterns before and during the pandemic had the lowest PCC risk. Finally, results were similar in sensitivity analyses in which alternative definitions of PCC were used and when participants with depression, memory problems, headache, fatigue, and brain fog were excluded.
Conclusions
In summary, the researchers observed an association of multiple sleep health dimensions before and early in the pandemic with a reduced risk of developing PCC.
A composite of early chronotype, low insomniac symptoms, seven or eight hours of sleep, and the absence of snoring or frequent daytime dysfunction showed an inverse relationship with PCC risk. There was an association between higher pandemic sleep quality and reduced PCC risk.
Before and during the pandemic, subjects with healthy sleep had the lowest risk of developing PCC. The predominantly White and middle-aged or older cohort limits the generalizability of the findings.
The results might not apply to currently dominant SARS-CoV-2 variants, given that PCC incidence differs by variant. Future studies should determine whether improvements in sleep health could mitigate or prevent PCC symptoms.
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