A Longitudinal Analysis of COVID-19 Lockdown Stringency on Sleep and Resting Heart Rate Measures across 20 Countries

Lockdowns imposed to stem the spread of COVID-19 massively disrupted the daily routines of many worldwide, but studies to date are mostly confined to observations within a limited number of countries, based on subjective reports and survey from specific time periods during the pandemic. We investigated associations between lockdown stringency and objective sleep and resting-heart rate measures in 113,000 users of a consumer sleep tracker across 20 countries from Jan-Jul 2020. With stricter lockdown measures, midsleep times were universally delayed, particularly on weekdays, while midsleep variability and resting heart rate declined. These shifts (midsleep: +0.09 to +0.58 hours; midsleep variability: –0.12 to –0.26 hours; resting heart rate: –0.35 to –2.08 bpm) correlated with the severity of lockdown across different countries and highlight the graded influence of mobility restriction and social isolation on human physiology.