The controversy over daylight saving time: evidence for and against

Abstract

Purpose of review Biannual clock changes to and from daylight saving time have been pervasive in many societies for over 50 years. Governments are considering abandoning this practice and choosing a single permanent time. Recent findings Our endogenous circadian clock follows our photoperiod, which changes over the year. The acute disruption caused by changing our clocks can affect safety (motor vehicle and on the job accidents), health (cardiovascular disease, drug overdoses, suicide), and human behavior (sport performance, generosity, and procrastination). Although abandoning the clock change could help avoid these acute harms, choosing the wrong permanent time could lead to chronic circadian misalignment, which could have even more profound implications for health, safety, and human behavior. Summary Ceasing the biannual clock change may be a good choice, but governments need to be mindful of which permanent time to adopt. Many regions of the world already follow the wrong time during standard time, and circadian misalignment would be amplified by moving to permanent daylight saving time. In many regions, Standard Time better aligns with our circadian clock, thus providing a more natural light cycle that minimizes circadian misalignment.

The practice of Daylight Saving Time in Canada: Its suitability with respect to sleep and circadian rhythms

“…While most studies on DST support the above conclusions and recommendations, there are still a number of reports with contradictory findings on the presence of disruptions and/or their severity (Antle, 2023 ). This seems to be attributable to uncontrolled variables that interfere with the interpretation of results (see below), including longitude and latitude of studied populations and their location within time zones, the actual dates of time changes that vary by country, and the presence of school breaks near time changes.…”

“…As a consequence, Thunder Bay should theoretically be in the Central Time Zone while Gaspé should be part of the Atlantic Time Zone. Overall, if permanent DST were to be adopted, citizens living in cities more than 30 min behind solar time would experience sunrise later in the winter and “social jetlag”, i.e., daytime activities would be permanently dissociated from optimal light exposure (Antle, 2023 ; Berument et al, 2010 ), leading to sleep loss. It is interesting to note that Saskatchewan, which maintains what is officially labelled as Central Standard Time (CST) yearlong, is oddly situated one hour west of the real solar CST.…”

“…The Canadian Society for Chronobiology has also made its own statement ( http://www.chronobiocanada.com/official-statements ). Antle ( 2023 ) has just published a review which focuses on more recent research. All these documents recommend the termination of the practice of DST in favour of permanent ST.…”