I don’t like daylight savings time. Actually, to be more accurate, I prefer daylight savings time (DST) but don’t like switching on and off of it. So with the time change this past weekend I decided to look into the benefits, or lack thereof.
Switching from DST to standard time is associated with an 11% increase in episodes of depression. Switching the other direction didn’t seem to have an impact. Hansen et all 2016
Kuehnle and Wunder (2014), on the other hand, found that the spring change is associated with a decrease in life satisfaction for about a week following the change. This was more apparent in households with young children.
Jiddou et all (2013) found a very moderate (~1%) increase in the rate of myocardial infarction (heart attack) immediately following the spring time change and a small decrease immediately after the fall change. This pattern was also found in a broader review of health records (Sandhu et all 2014) but did not appear to affect the overall occurrence of heart attacks.
Harrison (2013) found that both time changes decrease the overall amount of sleep and increase how fragmented the sleep is for a week or more after the change.
Smith (2016) found that sleep deprivation caused by springing ahead is connected with a higher incidence of fatal car crashes.
Zick (2014) asked whether daylight savings time increased the amount of physical activity. The participants in his study did not change their habits but they were all from states such as New Mexico. The author acknowledges that it may have more effect in other areas. I would be interested to see a similar study in a place like Edmonton where we have significantly more variation in the amount of daylight we get at different points in the year. It is, in fact, one of the reasons I don’t like standard time: the days are already quite short so I would prefer to have daylight after work which is when I prefer to be active.
What about energy efficiency? The reason daylight savings time was started was to conserve energy by taking advantage of more daylight hours during the work day; the question is whether it still has an energy efficiency benefit.
This is one that is potentially impacted by geographic region because climate and hours of daylight should both have an impact. It also may depend on whether you look at residential or commercial efficiency, or both. Unfortunately, these factors have not all been considered and research hasn’t been carried out in enough regions to say yes or no as a whole. The mixed results of a few studies that do exist include:
- Lighting use decreased but heating and cooling increased in Indiana (Kotchen & Grant, 2011)
- In a review of research already done Aries and Needham (2008) found that improvements in lighting efficiency were small (0.5%) and tended to be overrun by increases in other energy uses, especially gasoline use.
- Globally, the use of daylight over artificial lighting in commercial buildings can result in a decrease in lighting use of more than 40% (Bodart & De Herde, 2002). However, I wonder how this is impacted by building design and how much of a building can use natural daylight.
So, it seems to me, when you start looking at overall energy use, physical health, mental health, and the fact that farmers have always argued against it, that the days of daylight savings time should end. But that brings us to one last point, daylight savings time is practiced by many, but not all, people around the world and removing it completely would be a bit of a shift. But, it seems to me that it is a shift that people would care about for a few days a year for a couple of years and then we would get on with our lives.