235 Age and Chronotype Associated with Sleep Timing Changes During COVID-19-Related Lockdowns in the US

Bottary, Ryan; Fields, Eric; Kensinger, Elizabeth; Cunningham, Tony

INTRODUCTION: Global lockdowns implemented to reduce spread of the Coronavirus Disease 2019 (COVID-19) have offered unique insight into how sleep patterns change when typical social obligations are significantly reduced. Here, we aimed to replicate findings of sleep timing delays and reduced social jetlag during lockdown using a large, regionally-diverse sample of participants from the United States (US). Further, we conducted exploratory analyses to determine if observed sleep changes were associated with age and self-reported chronotype. METHODS: A sample of 691 US adults (age 18-89) completed the Ultrashort Munich Chronotype Questionnaire twice during the same assessment: once querying retrospective memory for sleep patterns in the 6-weeks prior to February 1, 2020 (Pre-Lockdown) and a second time for sleep patterns in the 6-weeks prior to ~May 20th (Peak-Lockdown in the US). Participants also completed the abbreviated Morningness-Eveningness Questionnaire to assess chronotype. We compared sleep duration (SDur), sleep onset time (SO), sleep end time (SEnd), social jetlag (SJL; difference between work-day and free-day sleep midpoint) and social sleep restriction (SSR; difference between work-day and free-day sleep duration) Pre- to Peak-Lockdown. We conducted exploratory analyses to determine whether Pre- to Peak-Lockdown changes in these sleep metrics were associated with age or chronotype. Main analyses were preregistered with Open Science Framework (https://osf.io/4a3fx). RESULTS: During the Peak-Lockdown period, participants, on average, reported significantly later SO and SEnd times and significantly reduced SJL and SSR compared with the Pre-Lockdown period. Change in SJL and SSR Pre- to Peak-Lockdown was significantly positively associated with age and chronotype such that SJL and SSR decreased more during lockdown in younger participants and those with an evening chronotype. CONCLUSION: Our results support lockdown-associated sleep timing delays and reduced SJL and SSR. Younger age and evening chronotype were associated with greater reductions in SJL and SSR during lockdown. These findings suggest that individuals, particularly young individuals and those with an evening chronotype, experience greatest desynchrony between intrinsic and social sleep timing when conforming to typical pre-pandemic social schedules. SUPPORT (IF ANY): Harvard Medical School Division of Sleep Medicine T32 HL007901 (RB and TJC); Brandeis University NIH NRSA T32 NS007292 (ECF)