What's your opinion on daylight saving time?


Is daylight saving time the ultimate in efficiency, or is it living a lie? Here are some graphs that might help facilitate a discussion on this topic ...

With daylight saving time (DST), a whole geo/political area (such as a country) decides to set their clocks forward an hour during the 'summer' months (when the sun rises earlier and sets later) so that they can take advantage of the extra sunlight hours, without all the factories/stores/etc having to change their hours of operation.

Not all countries honor DST, and in some cases not even all the areas within a country agree to honor it. Here is a world map I created with SAS (similar to one I saw on dadaviz) that shows which areas do and don't honor DST. In general, it looks like most of North America and Europe honor DST, and countries that are close to the equator or in Asia tend not to.


Of course, it's not as easy as saying a country does or doesn't use DST -- different countries can also choose when they want to start and stop DST! For this part of my graphical analysis, I've created some graphs only for the US DST. But even plotting the data for just the US is a bit tricky, because when we start & stop DST has changed over the years. For example, in 2007 the date to go on DST moved from the first Sunday in April to the second Sunday in March, and the date to go off DST moved from the last Sunday in October to the first Sunday in November. Here's the calendar for the current year (2015) showing which days are/aren't DST days:


Looking at that calendar chart, it appears that we (in the US) are now spending over 50% of the year with our clocks adjusted forward in DST. Let's use a different chart that will make it even easier to see the percentages. We could use a bar chart with 2 bars, but I think a pie chart is more intuitive (a lot of people like to bash pie charts, but I think they are a good/intuitive way to show the data when comparing part-to-whole with a 2-slice pie). From this chart, it's evident that we're spending almost 2/3 of the year in DST!


Personally, I have mixed feelings about DST. I can see the advantages of using it in the summer when days are very long, but I think the US might have gone a bit overboard if we're spending over 1/2 of the year (actually about 2/3 of the year) living a lie and adhering to a fake time.

So, what's your opinion on DST? Does your area honor it? If your area doesn't honor DST, do your factories/stores/etc change their hours in summer and winter?



About Author

Robert Allison

The Graph Guy!

Robert has worked at SAS for over 25 years, and is perhaps the foremost expert in creating custom graphs using SAS/GRAPH. His educational background is in Computer Science, and he holds a BS, MS, and PhD from NC State University. He is the author of several conference papers, has won a few graphic competitions, and has written a book (SAS/GRAPH: Beyond the Basics).


  1. Michelle Homes

    As you can see in the Australia map, Queensland (the state in the North West not shaded pink) does not have DST. Our summer days start early (shortly after 4am) and I know some people choose to start work at 7:30am finishing at 3:30pm, if they can. There has been much debate to align the state with the other Eastern states to help with interstate business. http://www.abc.net.au/news/2015-01-28/queensland-election-greens-two-year-daylight-saving-trial/6051926

  2. Why not live in GMT (24hrs economy world wide) and then adjust your habits to what is local the most sensible. There was a time every village had his own time (before travelling & communications). A next step for humankind?

    • Robert Allison
      Robert Allison on

      Since almost everyone uses their phone to tell the time these days (instead of a watch), the possibilities are almost limitless! :)

  3. I was thinking that there were counties in Indiana that did not go to DST, but I guess they standardized that in 2006 (though not their time zones!).
    I like the map, but one minor modification I might consider would be make the equator and/or the tropics in a slightly different color than the other lats and longs. The vertical center of the map is about 20 degrees North, which is good in that it better centers the land masses; but the variability in lengths of days is a function of distance from the equator, which is thrown off by that shift.

  4. Here in the UK we have daylight saving time. During the winter we observe GMT and in the summer, British Summer Time, an hour ahead. A few years ago there was a proposal to move us to single/double summer time - an hour ahead of GMT in the winter and two hours in the summer. The argument was that it would reduce accidents by making evenings lighter, and bring us into line with the rest of Europe. But for us in Scotland, this would mean facing a midwinter sunrise at some time around 10am. Maybe the idea of kids going to school in the dark finally stopped it happening!

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