Daylight Saving Time is a huge mess

Daylight Saving Time (DST) is a huge mess. For example, what is the time difference between Paris and Houston? It’s seven hours today. Yesterday it was six. A couple weeks ago it was seven.

Countries observe DST at different times or not at all. Even within one country it can be complicated. For example, the US generally observes DST. But Arizona, Puerto Rico, Hawaii, U.S. Virgin Islands, and American Samoa do not. And even within Arizona, the Navajo Nation does observe DST.

I wish everyone would take a few minutes to learn about universal time, UTC. It is essentially the time in Greenwich, England except it ignores DST. Learn how your time relates to UTC and use UTC when communicating with people who don’t share your time system. This allows, for example, a group to announce the time of a conference call in UTC and let everyone convert that to their local time. This is so much simpler than “your time”, “her time”, “his time” etc.

It’s also convenient to let people know how your time zone relates to UTC. For example, Houston time is UTC-6, i.e. six hours behind UTC. When someone asks in an email what my time zone is, maybe so they could call me during normal business hours, I may say Central Time, UTC-6. (Or in the summer, UTC-5.)

[The abbreviation UTC is an odd compromise. The French wanted to use the abbreviation TUC (temps universel coordonné) and the English wanted to use CUT (coordinated universal time). The compromise was UTC, which doesn’t actually abbreviate anything.]

Update: I’m not suggesting that people set their watches to UTC. Time zones are necessary. And if part of the world wants to have DST and another part doesn’t, vive la différence. I’m only suggesting that people use UTC when communicating with others outside their time zone.

Related post:

Software engineering and alarm clocks

78 thoughts on “Daylight Saving Time is a huge mess

  1. Not to mention trying to deal with financial market data. EST is the time most US markets are marked in. But then DST shows up and now you have to shift your market data times around if you’re not in the EST timezone or not on DST for the US. And if you’re dealing with UK markets, or AUS markets…, what time did the market open? Hell, I don’t know, last hour, next hour. Bah! Get rid of all timezones and just have a single time for the entire planet. We just do stuff at different times from longitude to longitude. I get up at 15:00 UTC and go to sleep at 6:00 UTC. Brits get up at 7:00 and got to bed at 22:00. There, done, no more nonsense.

  2. I fail to see how referring two different “local” times to a third, “universal” time is an improvement over just referring the two local times to each other. Now, instead of dealing with a one-stage, two-term conversion, you have a two-stage, three-term conversion. The only possible way in which it might be “better” is that, carried out universally, it leads to a centralized, or “star,” topology rather than a point-to-point one, hence fewer “edges” — but that’s graph theory, and is that REALLY a valid talking point here?

  3. What an insightful article. Perhaps next time you could introduce us to the metric system or, better yet, SI.

  4. Daylight Savings Time is a travesty. A solution with no problem. If someone needs to get up earlier or later because the sun is out at a different time, THEN JUST DO SO. Dumbest idea ever.

  5. I don’t prefer different time zones for different countries. In the whole world, there should be only one time. Clocks are created to do everything with some specific time and they are created by human (in the universe, there is no calendar). If something is going to happen, for example the Britain’s Royal Wedding, which is going to telecast in many countries then we can say that it will be telecast on 10 PM, and every countries can tune at the same time (10 PM). There will be no need to calculate the time of telecast for each country. Time zones are really big headache for everyone and special international software developers.

    Similarly there is no need to adjust with leap second. If we do not count leap seconds then how much difference will it REALLY create in the real world?
    Time is maintained by us for our day-to-day activities, not for time itself. Why to bother that much? Scientists have always problem with the concept of KISS (Keep It Simple Silly), they just know how to make things complicated!

    There are many other things in the world which are creating complex problems, for example units of weight, distance, temperature, speed etc; these should also be standard in all countries. A committee should be created to choose the best from them and those should be standardized in all countries. If any country do not follow it, it should be boycotted.

  6. I’d happily vote for both of the following items…

    1. We adopt daylight savings time ALL of the time. Let’s just stop adjusting our clocks. This alone would (after a little up-front IT cost) save our business untold hours every year.

    2. We all adopt UTC as THE time, everywhere. Yes, it would be a little weird for the first few weeks – only a handful of people would be working from 9 to 5 – but the massive benefits would soon have us wondering why in the world we didn’t do it sooner.

  7. I have UTC on my watch in the ‘second time zone’ slot. It’s a Casio Pathfinder with radio sync so I just set my current time zone and it takes care of the rest. I just missed the automatic no-more-DST adjustment of a few days ago.

    The whole DST thing is absurd of course. Weird thing is I only hear/read people complain and never hear anyone say how it’s so great. I mean people will comment how it’s so nice to ‘have an extra hour’ or some such nonsense but never something like ‘well we saved $5B in energy expenditures because we fiddled with your clock’. It is an absurd notion that farmers (or anyone) rely on the clock to tell them when to milk the cows or do anything that’s sun dependent. They use the Sun to tell them when it’s time to do X, not a clock. If DST saves us energy, why not simply admit our timezones are incorrect and permanently adjust them? If an hour shift saves energy in the Summer, wouldn’t it also in the Winter or vice versa? I mean the whole thing is mind boggling. If an hour time difference really had a measurable effect on energy consumption or anything for that matter we’d have benefits to living on the border of timezones, right? Clearly our local time doesn’t really match the Sun anyway so why shift it?

    Then there’s the whole thing about people being late for appointments or worse, getting into accidents because they’re more groggy than usual. You only need a small percentage increase in accident rates to get a measurable effect in a large population. If 10 extra people die the morning after a time change, is that worth the trouble?

    Pick reasonable timezones for areas on Earth and keep ‘em that way. Clearly the local time doesn’t matter one iota (note how crooked the time lines are and how) so abolish the madness.

    Sorry, no idea how to affect this.

  8. This is a perennial issue – particularly for the reasons stated regarding various local governments wanting to placate the biases of their particular constituents. It would be a significant benefit if the business community developed a standard approach for dealing with this. With so much work conducted internationally, the idea of a standard 9 to 5 work day is long gone. However, it would be nice to not receive phone calls at 3am because an account manager in Florida doesn’t understand the time difference in relation to Melbourne, Australia! ;-)

  9. I have not seen this mentioned here yet. I thought the primary justification for DST, other than for farmers, is so that your shades won’t fade.

    People sleep with curtains drawn, and open them when they wake up. If they are still sleeping when the sun is up, the curtains will fade faster.

  10. Here in Russia, I find very useful to describe local time zones as UTC+4 (Moscow), UTC+9 (Irkutsk), UTC+11 (Khabarovsk) – Russia is a huge country!
    Non-IT people in Russia usually use Moscow-based time shift (Moscow+4h etc).
    In software design I use UTC time for storing date-time values.

    DST was a mess, I agree. I’m happy it was gone in Russia. Every half-year switching was hard for healthy feeling.

    As to leap seconds, it is inevitable ambiguity. It describes Earth rotation slowdown, which is not strictly predictable (some estimation could be provided, though – I think, estimation error should be about 1 second per 100 year). Satellite systems (like Navstar/GPS) use time without leap seconds, but it is also a mess to keep it in mind in data processing (there is a 15 seconds difference with UTC as far as now).

  11. UTC Universal Time Constant
    Imagine the hassle when trying to write date&time stamps to a DB using a DST clock. I realised a longtime ago, I’m ancient, that mainframes used GMT to log data to a DB. This avoids the Autumn duplicated hours problem. Especially when you try to back out ( roll back ) a transaction.

  12. @colin dick

    I think there’s no disagreement about storage. Storage of time should always be in UTC or a fixed time zone.

    Presentation is another thing altogether. The same time value can and should show up differently for different users in different time zones.

  13. Is it really that big of a deal? Regional differences are an inevitable result of different, free political jurisdictions with different preferences for how to handle time. Whenever it matters on a large scale, computers can automatically handle the particulars.

  14. @human mathematics
    “Computers can automatically handle” is partially true but computers can handle it because “programmers have implemented” with great amount of efforts. Programmers have to care a lot on this, it is the biggest headache for them (saying because, I am a programmer too).

  15. human mathematics: I’m all for regional differences. If the people of one country want to set their clocks ahead 37 minutes on Fridays, that’s fine with me. It might be kinda nice to start every weekend early. Maybe they could set their clocks back on Tuesdays.

    But if they did that, I would hope they wouldn’t expect me to keep track of their quirky system. If I were scheduling meetings with them, it would be thoughtful for them to state the time in UTC.

  16. DoMBAR:

    The Internet Time or Beat time was invented by the watch company Swatch, in Switzerland.

    It is based on Switzerland local winter time.
    So is out by 1 hour from GMT/UTC (This is 41.666 beats in their system)
    Instead of dividing the day into degrees they divide the day by 1,000 and call each 1000th of a day a beat.
    So midday is 500 beets.
    1 24th of a day or 1 hour is 41.666 beats.

    As they are out by one hour from UTC, you will need to add or take away 41.6666 beats when converting.

    Not the best system in the world and I dought there are many people that would use it.

    I invented a similar system to this as a joke in the 80’s.
    See http://markagius.co.uk/webpages/contents.htm?SubPage=TenHour.htm

  17. @human etc.: ‘Free political jurisdictions’ can maintain any time they like. But -my- freedom allows me to then completely ignore them because they’re not willing to cooperate with others.

    Computers can handle the complexity of systems far greater than trivialities of time change. One of the questions is how do you keep all these systems up to date with the latest time zone quirks? My car has a clock that adjusts automatically for DST. Worked great in 2005. Then the DST date changed and the DST settings can’t be updated. We used FC4 linux at work. Its DST settings were also wrong. To keep logs in sync we had to update timezone data. MS has had to release multiple patches to make DST related changes.

    It’s a frackin’ pain in the rear. Abolish DST or at least leave the heck alone.

  18. @negativeland

    The Soviet Union does not exist anymore, but the President of Ukraine would like to have his own little version of it.

  19. @Anton

    Yeah right, and Putins just chilling in his house in the countryside and has completely resigned from politics. Dude, that guy still holds the strings (and the antique vases).

  20. The biggest issue I have with the bloody seasonal time change from DST to STD time is that when it happens, the computer takes off one hour from all my PREVIOUSLY WRITTEN files regardless of whether I want to have my files reflect actual local time, or not.

    It’s high time we got rid of this useless seasonal time change. It has no purpose in a modern society.

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