Every year I hate the transitions into and out of Daylight Savings Time*. Why do we still need this? Wasn’t it set up for World War I? Is it really worth the hassle?
- 2006
- When I wrote this page, I thought we should have DST year round.
- 2012
- I grew to accept the sunrise benefits of DST. Also see this diagram[1] and try out different cities. Based on the “days it’s light when you wake up” and “days it’s light when you leave work” it seems like DST may be better in northern cities and worse in southern cities. I’ve lived in southern cities of the U.S. so that may have led to my dislike of DST.
- 2015
- I learned that the preference depends in part on where you live. See this analysis[2]. Also see this set of reasons for keeping DST[3].
- 2019
- I learned that there are downsides of year-round Daylight Saving Time. See this article[4].
TL;DR: which you’ll prefer depends on whether sunset or sunrise matters more to you, and whether you’re more annoyed by the twice a year time change or more annoyed by many months of poor sunlight. See this visualization[5] and put in your preferences.
* Although daylight saving is the correct term, more people use daylight savings, as can be seen on Google Trends[6]. I used savings for the title only.
Benefits
What are the reasons for Daylight Saving Time?
- It shifts summer daylight to evening hours, when it can be enjoyed more. I think this is a good reason.
- It saves energy, because people don’t use their lights as much in the evening. Back when lights were the main use of energy, I think this was a bigger justification.
- It reduces accidents, because people are less likely to be driving in the dark. Hm.
- It keeps sunrise time in a narrower range, as you can see from the blue line on this graph[7]. Without DST, you either have the sun rising way too early in summer, or you have the sun rising way too late in the winter. :-(
Costs
The costs to Daylight Saving Time have increased over the years. It used to be that the only times you cared about were local. Each local area had its own decision about whether to use Daylight Saving Time and when to start and end it.
- There’s a cost when dealing with someone who follows a different set of rules. For example, if Arizona uses different rules than Texas, you can’t always assume that they’re one hour apart. It depends on what day it is. It’s hard to measure this cost; it’s a small cost paid by lots of people. As global trade increases, this cost gets higher; rules are different in each country[8].
- There’s a cost of actually switching times. As the number of clocks in the household has increased, this cost has gone up. VCRs are the typical victims, but we also have computers, ovens and microwave ovens, thermostats, DVD players, televisions, radios, answering machines, cell phones, sprinkler timers, and more. Many devices are able to switch the times automatically, but this is completely messed up when the U.S. changes the rules, as they are going to do in 2007. All these devices will switch on the wrong day!
Why we should get rid of it
The main argument I see for Daylight Saving Time is that it gives us more evening hours with daylight. Since people are more likely to be awake and active in the evening (after work) than in the morning (before work), Daylight Saving Time shifts the daylight to a time when it’s more useful. In these diagrams, the yellow is daylight, blue is “normal” work hours (8 to 5), and green is evening time at home:
Winter:
Summer:
Summer with Daylight Saving Time:
Conclusion
(2006) I think we should use Daylight Saving Time all year round. If wasting daylight on mornings in the summer is bad, then it’s even worse to waste it in the winter, when there’s less daylight! Look at the wasted morning daylight in the Winter diagram; wouldn’t that be better if available in the evening?
If we had Daylight Saving Time year round, we’d eliminate all the costs of having it, keep all the benefits, and gain new benefits—more usable daylight in the winter. In essence, we’d be shifting everyone’s time zone westwards by one hour. It’s a simple solution.
Update: [2014-03-08] By 2012, I grew to accept DST as it currently is. I used to care more about sunset but as I got older I started caring more about sunrise time. Morning sunshine affects circadian rhythms; this greatly helps my sleep patterns. Daylight also affects Vitamin D, which is especially important to get in winter. For me, personally, the items in the Benefits section above are more important to me than they used to be, and the things listed in the Costs section are less important than they used to be. Most of my clocks (including computer and cell phone) automatically adjust, so the transitions are less and less annoying every year. The one thing I’d like is for the government to stop changing the rules.