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Health Impacts of Daylight Savings Time


Contributor Ronnie Du


At first glance, daylight saving time seems to have fast become an unnecessarily divisive and needlessly contentious topic among Canadians. However, beneath the bickering, there lies a bonafide scientific debate. Meant to delay the rise and fall of the sun by an hour during the earlier and longer days of the more temperate months, daylight saving time was adopted in 1918 by the Canadian government and is now observed by 70 countries around the world. Although today it is heralded as a green measure (as it brightens evenings), as health data shows, these energy savings could be coming at the cost of human life. Across Canada, as provinces set their sights on legislation or referendums abolishing the biannual clock change, here is what you need to know about the effects of daylight savings.


The spring shift forward usually marked by a jump in heart attacks—in 2014, a study showed a 24 percent rise in heart attacks the Monday after the switch to daylight saving time, and in Sweden, researchers observed a 6.7 percent spike in heart attack risk in the three days following the clock change. However, it should be noted that when clocks return to standard time in autumn, there is a corresponding decrease in heart attacks as well. Although these studies did not specify the cause of these changes, the predominance of patients who do suffer heart attacks during the spring leap are already susceptible to cardiovascular disease—a concern that is not directly relevant to most students. More pertinent to readers of the BMSA blog might be the spike in car accidents in the week after March 14. In a 22-year study published in Current Biology, scientists at the University of Colorado at Boulder recorded a 6% rise in fatal automobile accidents in the week subsequent to the spring forward to daylight saving time—a phenomenon resulting from fatigue and circadian misalignment. And for Western students in Western Canada—your westerly whereabouts further exacerbate your risk of death, as in spite of your later-rising sun (relative to students in the east), you must still wake an hour earlier for lectures and tutorials, compounding your already-considerable midterm exhaustion.


Additionally, the leap forward is accompanied by a multitude of mental health concerns. In particular, the autumn change is associated with an 11% surge in patients being treated for depressive symptoms at hospitals in Denmark. Furthermore, the autumnal shift to standard time comes at a cost of one hour of evening light—which could trigger SAD symptoms for some, due to the suppression of melatonin and serotonin by the lack of sunlight.


This is not to say that the effects of daylight savings are entirely negative—whereas the benefits of DST tend to be year-round, this is not the case for negative effects, which tend to occur immediately following clock changes and dissipate shortly thereafter. Lighter evenings are shown to reduce the occurrences of crimes such as robbery, and there are slight energy savings which also come as a consequence of daylight savings time. However, whether or not these benefits are worth the steep annually-renewing subscription price we pay is debatable.



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