Background: Sleep disorders are widespread but usually overlooked health risk factors.

Objectives: To explore the influence of pre-existing sleep disorders on the susceptibility, severity of coronavirus disease 2019 (COVID-19) and long COVID.

Methods: We searched PubMed, Web of Science, and Embase for relevant articles from inception to Oct 27, 2023. Sleep disorders including obstructive sleep apnea (OSA), insomnia, insufficient or excessive sleep duration, night-shift work, and other sleep disorders. The effect sizes were pooled odds ratios (ORs) and 95% CIs. PROSPERO registration number: CRD42024503518.

Results: A total of 51 studies (n=9,015,425) were included. Participants with pre-existing sleep disorders had a 42% increased risk of COVID-19 susceptibility (OR=1.42, 95%CI 1.26-1.60), 28% of hospitalization (OR=1.28, 95%CI 1.18-1.39), 36% of ICU admission (OR=1.36, 95%CI 1.14-1.62), 41% of mortality (OR=1.41, 95%CI 1.17-1.70), and 29% of long COVID (OR=1.29, 95%CI 1.17-1.41). OSA was associated with COVID-19 susceptibility, hospitalization, ICU admission, mortality, and long COVID. Insufficient sleep duration elevated the risk of COVID-19 infection, hospitalization, and long COVID. Populations with insomnia were at higher risk of suffering long COVID. Night-shift work increased the risk of COVID-19 infection and hospitalization. 

Conclusion: Pre-existing sleep disorders play an essential role in the whole COVID-19 clinical course. Thus, detection, dynamic monitoring, and intervention should be initiated as soon as possible to alleviate the short- and long-term effects of COVID-19.