The effects of daylight saving time and clock time transitions on sleep and sleepiness: a systematic review

Background: Daylight Saving Time (DST) has been a subject of debate concerning its impact on human health, particularly sleep patterns and daytime sleepiness. This systematic review aims to synthesize existing research on the effects of DST on sleep quality, duration, and sleepiness, identifying gaps, and setting a future research agenda. Methods: A comprehensive literature search was conducted across multiple databases, according to the PRISMA guidelines. The included studies were those that examined the impact of DST on sleep outcomes and daytime sleepiness in populations aged 6-85 years, using objective and subjective measures of sleep. Results: The review analyzed 27 studies, revealing heterogeneous findings. The transition to DST was associated with adverse effects on sleep duration and quality, as well as increased sleepiness, more evident in evening chronotypes. Conclusions: Although the transition to DST appears to negatively affect sleep patterns, particularly in spring and among evening chronotypes, definitive conclusions are hampered by methodological inconsistencies and external influences. This review highlights the need for future research employing standardized, objective measures across representative samples to elucidate the true impact of transitions to and from DST and the difference between standard time and permanent DST on sleep and daytime functioning. Addressing these gaps is crucial for informed public health policies.