The effects of daylight saving time clock changes on accelerometer-measured sleep duration in the UK Biobank

We explored the effects of daylight saving time (DST) clock changes on sleep duration in a large accelerometer dataset. Our sample included UK Biobank participants (n= 11,780; aged 43-78) with accelerometer data for one or more days during the two weeks surrounding the Spring and Autumn DST transitions from October 2013 and November 2015. Between-individual t-tests compared sleep duration on the Sunday (midnight to midnight) of the clock changes to the Sunday before and the Sunday after. We also compared sleep duration on all other days (Monday-Saturday) before and after the clock changes. In Spring, mean sleep duration was 65 minutes lower on the Sunday of the clock changes than the Sunday before (95%CI -72 to -58 minutes) and 61 minutes lower than the Sunday after (95%CI -69 to -53). In Autumn, the mean sleep duration on the Sunday of the clock changes was 33 minutes higher than the Sunday before (95% CI 27 to 39 minutes) and 38 minutes higher than the Sunday after (95% CI 32 to 43 minutes). There was some evidence of catch-up sleep after both transitions, with sleep duration a little higher on the Monday - Friday than before, although this was less pronounced in Autumn. Future research should use large datasets with longer periods of accelerometer wear to capture sleep duration before and after the transition in the same individuals, and examine other aspects of sleep such as circadian misalignment, sleep fragmentation or daytime napping.