Objective Circadian and sleep disruption may increase the risk and severity of SARS-CoV-2 infections, but the role of night shift work and disturbed sleep in the development of long-COVID remains inadequately investigated. We prospectively examined the association of night work and sleep disturbances with risk of long-COVID.

Methods We followed participants of the COVICAT study, a population-based cohort of adults in Catalonia, Spain between 2021 and 2023. Night shift work and sleep characteristics were assessed in 2021. Long-COVID was defined as the report of persistent symptoms (>3 months) after a SARS-CoV-2 infection. Poisson regression analysis was performed to evaluate the independent and joint effects of night shift work and sleep disturbances including chronic insomnia with risk of long-COVID. Analyses were stratified by sex, body mass index and chronotype.

Results During the two-year follow-up, 284 of the 1899 newly infected participants reported long-COVID symptoms. Compared to day workers, night shift workers had 88% higher risk of developing long-COVID [95% confidence interval (CI) 1.29–2.72], after adjusting for potential confounders. The risk further increased among night workers with obesity. Chronic insomnia in the general population was associated with 42% increased risk of long-COVID (95% CI 1.12–1.78). Night workers with chronic insomnia had a 2.7 fold higher long-COVID risk (95% CI 1.60–4.51) compared to day workers without chronic insomnia. Associations persisted in various sensitivity analyses.

Conclusions Our findings from a large prospective cohort indicate that night shift work and poor sleep are independently and jointly associated with a higher risk of long-COVID.

Key terms COVID-19; insomnia; long-COVID; night shift work; night work; SARS-Cov-2; shift work; sleep disruption; sleep disturbance

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