Sleep and circadian problems during the coronavirus disease 2019 (COVID-19) pandemic: the International COVID-19 Sleep Study (ICOSS).

This protocol paper describes the development of an international collaboration to survey several thousand adults from different countries around the world about their sleep during the coronavirus disease 2019 (COVID-19) pandemic. It is based on the development of a harmonised survey with 50 questions (106 different items) on sleep habits and sleep symptoms that permit comparability of information. The harmonised questionnaire may be used in anonymous cross-sectional surveys, and the instruments within the questionnaire may also be used in prospective studies and clinical studies. The aim was to develop a questionnaire to sample a variety of sleep-wake disorders and other symptoms likely to be caused by prolonged social confinement or by having had COVID-19. The questionnaire was designed to be: (a) simple and, (b) free to use, for research purposes, (c) multilingual, and (d) comprehensive. It can be completed in <30 min. By the end of June 2020, the survey questionnaire had been administered in Austria, Canada, China, Finland, France, Germany, Hong Kong, Italy, Japan, Norway, Poland, Sweden, UK and USA. Research questions to be addressed by the pooled data derived from the participating sites focus on describing the nature and rates of various sleep and circadian rhythms symptoms, as well as their psychological and medical correlates, that arise at various points during the COVID-19 pandemic.