# Are there lingering effects of Daylight-Saving Time on sleep and health estimates of an Australian population?

## TL;DR

This study examines whether Daylight-Saving Time has lasting effects on sleep and health in an Australian population.

## Contribution

The study is the first to investigate the lingering effects of DST on sleep and health beyond the immediate transition period.

## Key findings

- People in DST states tended to go to bed and wake up later than those in ST states.
- No differences in total sleep time or sleep onset latency were found between DST and ST states.
- No significant impairment in sleep health was observed in DST states compared to ST states.

## Abstract

Research has examined acute sleep effects at the immediate transition onto Daylight-Saving Time (DST), culminating in a sentiment that it should be abolished. These effects could be theorized to continue well-into the DST period. The current article aimed to address this gap, investigating the effect of DST on sleep during the middle-late stages (2–4 and 6 months) of the DST period. A retrospective, cross-sectional design was used to compare subjective data of two nationwide surveys of the Australian population; one population-representative sample, and a convenience sample of those with chronic Insomnia. Respondents were categorized based on whether they were from a DST state or permanent Standard Time (ST) state. We then compared sleep behavior and tendencies in sleep health between DST and ST states. Overall, both samples consistently demonstrated that those from DST states tended to go to bed later and, particularly, rise at later clock times than those from ST states. Importantly, despite a delay in the timing of sleep we found no differences in reported Total Sleep Time nor Sleep Onset Latency; and no sign of impairment on any related health estimates. Very few sleep health variables reached significance (p < .05), and the vast majority of them suggested those from DST states were less impaired than their ST counterparts. We have found no evidence of impairment associated with DST well-into the DST period. Future studies should measure sleep and associated daytime functioning longitudinally and objectively to accurately assess the possible duration of any potential acute DST effect.