Lingering impacts on sleep following the Daylight Savings Time transition in the Project Baseline Health Study

Background The “spring forward” change to Daylight Savings Time (DST) has been epidemiologically linked with numerous health and safety risks in the days following the transition, but direct measures of sleep are infrequently collected in free-living individuals. Methods The Project Baseline Health Study (PBHS), a prospective, multicenter, longitudinal representative U.S. cohort study that began in 2017 launched a Sleep Mission in March 2021 to characterize sleep using patient-reported and wearable device measures, in free-living circumstances during the DST switch. Estimated sleep period duration, subjective restedness, and sleep quality were compared before and after the DST transition during specified timeframes. Results Of the total PBHS population of 2502 participants, 912 participants received an invitation and 607 responded by March 6th. Among those, 420 participants opted into the Sleep Mission (69.2%). The transition to DST resulted in both acute and lingering impacts on sleep. Acute effects included a 29.6 min reduction in sleep period ( p = 0.03), increases in the proportion of patients who reported ‘sleeping poorly’ (from 1.7 to 13.6% [ p < 0.01]), and with scores falling into the ‘unrested’ category (from 1.7 to 8.5% [ p = 0.046]). There was also a downward trend in the proportion of participants reporting being rested in the morning following the DST transition (from 62.7% on March 7 to 49.2% on March 14 [ p = 0.10]). Lingering effects included a 18.7% relative decrease in the daily likelihood of participants reporting restedness (from 49.2% in the week prior to the DST transition to 40.0% in the week after [ p < 0.01]). Conclusion The DST transition is associated with an acute reduction in sleep period, as well as an increased proportion of individuals reporting poor sleep and unrestedness. The DST transition also resulted in lingering impacts on self-reported restedness, lasting into the week following the transition. This work adds to a growing understanding of the persistence of impacts on sleep health metrics due to the DST transition.