O016 Daylight-saving time effect on sleep and wake of Australian population

Abstract Daylight-Saving Time (DST) has been linked to various health risks stemming from presumed sleep disruption following the clock change in the spring. In response, scientific bodies have called for DST’s abolition. However, few studies have explored the longer-term effects of DST on sleep health later in the DST period. To address this, we investigated the effects of DST on the Australian population of which about two-thirds goes onto DST in the summer period. Two surveys formed a cross-sectional component: one nationally representative sample of 1011 participants (assessed late in the DST period), and a convenience insomnia sample of 402 individuals (assessed in the middle of the DST period). Both groups in DST states reported later bedtimes and waketimes than those in Standard Time (ST) states, some differences reaching significance. However, there were no significant group differences in total sleep time, sleep quality, or daytime functioning during the analysis periods. To assess objective sleep across the transition period, under-the-mattress sensors followed 1096 Australians over a four-week period centred on the DST transition weekend (± two weeks). DST participants again showed significantly later bedtimes and waketimes than ST participants. Sleep duration was significantly less for DST states only on the night of transition (24 minutes). Sleep duration was no different between the states for the two weeks following DST transition. These findings suggest DST’s effects on sleep are small and limited to one night. Its effects on daytime functioning immediately following DST transition need equally careful investigation.