Résumé
To study the impact of the COVID-19 pandemic on sleep and circadian rhythms-two fundamental pillars for health-the collaboration International COVID-19 Sleep Study (ICOSS) was established. The present overview comprehensively discusses the findings from this collaboration. Involving sleep researchers across the globe, ICOSS used a harmonised questionnaire to cover changes in sleep and sleep disorders, as well as physical and mental health. Two survey waves were conducted, one in 2020 and another one in 2021. In ICOSS-1, a total of 26,539 people from 14 countries across four continents (Europe, Asia, North and South America) participated. In ICOSS-2, two more countries joined ICOSS, and 15,813 people participated. The focus in ICOSS-2 was on Long COVID. Participants accessed the widely disseminated online surveys in their native language. In the 20 papers published so far, the surveys have uncovered several novel findings, including how the pandemic impacted sleep patterns, the prevalence of sleep disorders, chronotype-based differences and sleep-immune system interactions. To the best of our knowledge, there is no other large-scale multinational study targeting the general population investigating the role of sleep and sleep disorders alongside a variety of psychological, biological, social and economic factors during the recent COVID-19 pandemic.