Martín Olalla, José MaríaMira Pérez, Jorge2026-04-072026-04-072025-03-19Martín-Olalla, J. M., & Mira, J. (2025). Assessing the best hour to start the day: an appraisal of seasonal daylight saving time. Royal Society Open Science, 12(3). https://doi.org/10.1098/RSOS.240727https://hdl.handle.net/10347/46590We provide an evidence-based position on the seasonal regulation of clocks daylight saving time (DST) that challenges position papers by sleep associations against the practice. We review the acute, short-term impact and the chronic, long-term impact of DST in the context of the changing ambient light conditions that characterize seasons at Extratropical latitudes. We highlight the association between DST, human physiology (photoreceptive mechanisms) and human daily life. We offer a perspective on the possible scenarios should clock regulations be abandoned.eng© 2025 The Author(s). Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.Attribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/Circadian misalignmentDaylight saving timeMotor vehicle accidentsMyocardial infarctionSleep deprivationSummer timejournal article2026-04-0610.1098/RSOS.2407272054-5703open access2054-5703