O072a The relationship between bedtime procrastination, habitual smartphone use, and sleep in young adults: Results from the Young Adult Health Study (YAHS)

Abstract Introduction A potential explanation for the relationship between screen-based digital technology use and poor sleep health is bedtime procrastination (alongside arousing content and circadian disruption from light emitting devices). This study aimed to provide insight into the mechanisms linking digital technology and sleep in young adults by exploring associations between bedtime procrastination (where individuals delay bedtime for no external reason), habitual smartphone use, and sleep duration. Methods Data from this study were drawn from baseline assessments of a larger randomised control trial examining an intervention to extend sleep in young adults. To enter the trial participants (N=99, aged 18-24; 70.7% female) reported typically sleeping <7hrs per night, and <6hrs on at least 2 nights per week. Participants wore an actigraph for two weeks to assess habitual sleep timing and duration. Average weekly habitual smartphone use was collected from a smartphone application. Standardised measures to assess other constructs (including bedtime procrastination) were also completed. Results Later average actigraphy derived bedtimes and waketimes were significantly associated with bedtime procrastination (r=.38, p<.001, and r=.28, p<.001, respectively), however, greater bedtime procrastination was not associated with average smartphone use (r=.13), sleep duration (r=-.13), or sleep disturbance (r=.16). Increased bedtime procrastination was associated with increased daytime sleep-related impairment (r=.45, p<.001), anxiety (r=.23, p<.05), and depression (r=.22, p<.05). Discussion Our findings do not support the ‘displacement’ hypothesis that screen use influences sleep health by displacing time usually spent sleeping. This result is inconsistent with past research showing a temporal relationship between bedtime procrastination and increased smartphone use.