COVID-19(14) individual(12) Sleep(10) pandemic(10) COVID-19 pandemic(8) less(8) sleep quality(8) Health(8) mental health(8) analysis(7) Insomnia(7) Result(6) Chronotype(6) participant(6) objective(6) age(6) Stress(6) Depression(6) reported(6) coronavirus(6) changes in(6) country(6) coronavirus disease(5) Symptom(5) Evidence(5) circadian rhythms(4) problem(4) affected(4) stratified(4) Sex(4)