The idea of shifting our clocks to make better use of daylight is as old as Benjamin Franklin, who first penned the idea while living in Paris in 1784 when he noticed people used candles at night and slept past dawn in the morning. However, the notion wasn’t given serious consideration until the early 1900’s, and during World War I the first laws were passed driven largely by economic considerations. Now 70 countries have instituted Daylight Savings Time to some degree.
Despite many adjustments since then, observance today in America is nearly universal, except in the case of Hawaii and most of Arizona. Arizona felt that with its hot climate, it argued that people prefer to do their activities in the cooler evening temperatures after the sun sets. Hawaii sits so close to the equator that its sunrise and sunset are consistent already and therefore has little need for extra light. Most countries located around the equator have opted out for the same reason.
The theoretical arguments for DST – lighter evenings mean lower demand for illumination and electricity – have been debated at length, but it was rather hard to prove. However, when Indiana adopted DST statewide in 2006, after previously observing it county by county, researchers were able to study before-and-after electricity use across the state. In a 2008 National Bureau of Economic Research study, the team found that lighting demand dropped, but the warmer hour of extra daylight tacked on each evening also led to more air conditioning use which more than offset the savings.
We miss the loss of an hour in spring and love the extra hour of sleep in the fall, but more evidence is showing a negative impact on our body clocks and health. In a 2016 study presented at the American Academy of Neurology, stroke risk has been found to be highest in the morning and the overall rate for stroke was 8% higher in the two days following DST. According to a 2012 study from the University of Alabama-Birmingham, the Monday and Tuesday after DST have also been associated with a 10% increase in heart attacks. Some of these results are reversed in the fall. Less understood is the impact on our circadian rhythms, the molecular cycles that regulate when we feel awake, when we feel sleepy as well as our hunger and hormone production levels. Kind of like how jet-lag can make you feel completely out of whack.
No matter your feeling, this coming Sunday, November 5 at 2:00am, Daylight Savings Time officially ends in America. Be sure to set your clocks back one hour or you might spend that extra time waiting rather than sleeping.