The association of insomnia with long COVID: an international collaborative study (ICOSS-II)

Objective: There is evidence of a strong association between insomnia and COVID-19, yet few studies have examined the relationship between insomnia and long COVID. This study aimed to investigate whether COVID-19 patients with pre-pandemic insomnia have a greater risk of developing long COVID and whether long COVID is in turn associated with higher incident rates of insomnia symptoms after infection. Methods: Data were collected cross-sectionally (May–Dec 2021) as part of an international collaborative study involving participants from 16 countries. A total of 2311 participants (18–99 years old) with COVID-19 provided valid responses to a web-based survey about sleep, insomnia, and health-related variables. Log-binomial regression was used to assess bidirectional associations between insomnia and long COVID. Analyses were adjusted for age, sex, and health conditions, including sleep apnea, attention and memory problems, chronic fatigue, depression, and anxiety. Results: COVID-19 patients with pre-pandemic insomnia showed a higher risk of developing long COVID than those without pre-pandemic insomnia (70.8% vs 51.4%; adjusted relative risk [RR]: 1.33, 95% confidence interval [CI]: 1.07–1.65). Among COVID-19 cases without pre-pandemic insomnia, the rates of incident insomnia symptoms after infection were 24.1% for short COVID cases and 60.6% for long COVID cases (p <.001). Compared with short COVID cases, long COVID cases were associated with an increased risk of developing insomnia symptoms (adjusted RR: 2.00; 95% CI: 1.50–2.66). Conclusions: The findings support a bidirectional relationship between insomnia and long COVID. These findings highlight the importance of addressing sleep and insomnia in the prevention and management of long COVID.