JAMA Network Open · 6 authors, 4 centres
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This cohort study of 1979 women from the Nurses' Health Study II found that healthier sleep before SARS-CoV-2 infection was associated with a lower risk of developing post–COVID-19 condition (PCC). Women with the healthiest sleep score (5 out of 5) had a 30% lower risk of PCC compared to those with the worst sleep (score 0 or 1). These findings suggest that promoting healthy sleep may be a modifiable factor to reduce the burden of long COVID.
**Background:** Post–COVID-19 condition (PCC), or long COVID, affects 20% to 70% of persons infected with SARS-CoV-2 and encompasses a wide range of persistent symptoms. Sleep problems are prevalent, affecting approximately 1 in 3 people worldwide, and have been linked to COVID-19 susceptibility, severity, and mortality. However, the association between sleep health prior to SARS-CoV-2 infection and risk of PCC had not been investigated. This study leveraged data from the Nurses' Health Study II (NHS II) to prospectively evaluate this association.
**Methods:** This cohort study included 1979 women from the NHS II who reported a positive SARS-CoV-2 test during 19 months of follow-up (through November 3, 2021). Five prepandemic sleep dimensions (chronotype, sleep duration, insomnia, snoring, and daytime dysfunction) were assessed in 2015-2017 and combined into a healthy sleep score (0-5). Two pandemic-era sleep dimensions (sleep duration and quality) were assessed at substudy baseline (April-August 2020). PCC was defined as having COVID-19-related symptoms lasting more than 4 weeks, self-reported on the final questionnaire. Poisson regression models estimated relative risks (RRs) and 95% CIs, adjusting for age, race/ethnicity, frontline healthcare worker status, lifestyle factors (BMI, physical activity, smoking, diet, alcohol), and comorbidities.
**Key Results:** Among 1979 women (mean age 64.7 years, 97.2% White, 42.7% frontline healthcare workers), 870 (44.0%) reported PCC. A healthier prepandemic sleep score showed a dose-response association with lower risk of PCC. Compared with participants who had a sleep score of 0 or 1, those who scored 5 had a 30% lower risk of developing PCC (RR, 0.70; 95% CI, 0.52-0.94; P for trend <.001). Among individual sleep dimensions, daytime dysfunction before the pandemic showed the strongest independent association (RR, 0.83; 95% CI, 0.71-0.98 in mutually adjusted models). Sleep quality during the early pandemic was also independently associated with lower PCC risk (RR, 0.82; 95% CI, 0.69-0.99). Participants with healthy sleep both before and during the pandemic had the lowest risk (RR, 0.64; 95% CI, 0.50-0.82) compared to those with consistently unhealthy sleep. Results were robust across multiple sensitivity analyses, including alternative PCC definitions, excluding hospitalized or vaccinated participants, and adjusting for mental health.
**Clinical Implications:** These findings suggest that healthy sleep prior to SARS-CoV-2 infection may be associated with a substantially decreased risk of developing PCC. The dose-response relationship and consistency across sensitivity analyses strengthen the evidence for a potential causal link. Given that sleep is a modifiable health behavior, these results highlight the need for further research on whether improving sleep health could prevent or alleviate PCC symptoms. The study's limitations include a homogeneous sample (97% White, all female), potential for self-report bias, and limited ability to detect modest associations for some subgroups. Future research should investigate sleep health interventions as a potential strategy for PCC prevention.