It's pretty astounding to me the number of pro-DST advocates in this forum. If you had hundreds of daily jobs on your platform and you happen to have some regular requirement to change them in unison, if a junior engineer said "let's just change the system clock to adjust for when we want the jobs to run", you would say no, because while it might be easy compared to changing the config for each of the jobs, the risk of ongoing errors, side effects, introduction of jobs that need to fixed in absolute time that you have to make the inverse change... It's a system nightmare.
In the summer the suns up at 5 am. But at 5am I am asleep. I could get up earlier but that's pointless since school and work doesn't start until 8.30.
So in stead of having an hour of sunlight before school and work we all change our clocks to have an hour of extra sunlight in the evening in stead, which fits our cultural preference for social activities.
We could also, as you say, change every single sign, post and display of opening hours for every school, business and organisation at the same time to achieve the same effect.
But in the real world changing the clock is simpler.
It's a fairly trivial change. We already have timezones, which exist to deal with the fact that the sun comes up at different times in different parts of the world. We already have to design everything around the assumption that timezones can change, since people sometimes move to different parts of the world. All we do is cause, for an entire timezone, that it becomes a different timezone at one point in the year, and switches back later. This ensures that the sun continues to come up at a consistent time. The main issue it causes is to make the lives of programmers slightly more difficult, which I am sure they can cope with...
I guess that is what I'm trying to show in the above example. You could technically shift your UTC jobs by running your own NTP server and desyncing it from UTC by the offset you want. It would work, but it would be nightmare fuel. And possibly this is an even better example of what DST is doing.
Some jobs should run every day at 8 am (e.g. torn on the temporary speed limit on front of the school), vs tasks that should actually run every 24h (e.g. feed the bacteria in exact time intervals)
Imagine having a solution that already works with changing system clock but then some very big very important very senior very developer shows up and launches a multi-year project to redesign this, potentially opening pandora box of endless bugs. PhD in Job Security, typical shit I see in corporate.
To be clear if I showed up to a company running their own company NTP server that they desync twice a year to make timings work - I would absolutely try to migrate them away from that. Now if they are doing that there is probably bigger fish to fry... but it would be on the list.
In Seattle, without DST, sunrise happens at 4:11am. Because of DST, it's pushed back an hour later to a more reasonable 5:11am.
I am not awake at 4am, I have no use for sunlight at 4am, and I don't want the sun appearing that early. That hour of early sunlight is wasted for me. Plus with DST, the sun sets an hour later, at 9:11pm, a time I am actually awake, and I can actually go outside and use the extra sun.
And, with permanent DST (which is what many people are advocating for), then in winter sunrise is at 9am in Seattle, which is far too late. I do not want to drive to work in the dark, before sunrise. So I want standard time in winter, pushing sunrise an hour earlier to a more reasonable 8am.
In both situations (summer and winter), modifying the time via DST benefits me and gives me better use of sunlight.
Then we should have timezones based not just on longitude, but also latitude. So northerly locales can get some sleep in the spring/summer/fall.
> If your issue is when work is scheduled, well businesses set their own hours, not the government.
Ah, someone who doesn't have kids in school/camp/some random activity yet.
We know how this goes in China (one time zone, no daylight savings time). Coming home from the bar in Beijing with the sun showing up at 4 AM was quaint back then, but I'm definitely glad we have DST in the states.
Beijing is a bad example, because all of China actually has Beijing time. It gets confusing in Xinjang, which is 2 hours in the "wrong" timezone. But that doesn't mean that people start work at 8:00 in complete darkness, they just start at 10:00 wall time.
I think the talk of daylight savings time is a distraction, in the end it is arbitrary what the clock says. As a society we need to negotiate when (in celestial time) we want to do certain activities. For example, there are a lot of studies that school starts to early (relative to sunrise and the average bed time of teenagers). But the school starting time has to be decided politically. And reduced working hours or later start times have to be negotiated by trade unions, politics etc.. That's a lot more messy than just shifting wall time.
Urumuqi actually delays store openings/closings (department stores open at 11AM, for example), so it isn't that bad. Beijing time in Beijing should be accurate, but without DST, the sun rises way too early in the morning. But even then the schedules are still fixed, just the Chinese enjoy their night life, so the sun setting at 6-7PM in the summer isn't really a big deal.
Our school schedules are set by weird rules involving when school bus capacity is available. But in general, 9AM is about when school starts (for my son's K-8, its 8AM here for K-5s), or summer camp session starts, or whatever. My schedule is so influenced by my kid these days, it happens to correspond to rush hour, which sucks, because everyone else's schedules are intertwined (so traffic).
I WFH and can definitely set my own work hours. Which is why its 12:30 AM and I still haven't gone to bed yet.
If you are looking for an example I did some contract work for a company in Turkey that implemented winter hours and summer hours for their office after abolishing DST in 2016. As far as I understand it, it's fairly standard across the country.
> businesses set their own hours, not the government
In plenty of countries the government decides the opening hours of shops, restaurants and sometimes even offices. Labour laws and nighttime pay are coupled to the hours on the clock. Hours you can make noise is decided by government. Germany has the mid-day resting hour (Mittagsruhe).
Yeah, as someone who lives in Vermont, you could talk me into permanent DST. That would move the winter sunset from, say, 4:21pm to 5:21pm, which would mean I'd get enough twilight for a short walk after work. And Maine is even further east and north in the same time zone, so they have an even earlier sunset. On the other hand, Vermont's standard time sunrise around 7:20 is reasonable enough.
Parts of Vermont have traditionally coped with this by having an 8-4 workday instead of 9-5.
But the reality is that Vermont gets only about an hour of daylight outside working hours, depending on local customs. People have extremely strong preferences about how that hour gets split up.
Permanent DST is just a synonym for "let's all agree to wake up an hour earlier." The same change could be affected by e.g. schools and businesses agreeing to open at 8am instead of 9am. (Of course that would be wildly unpopular so permanent DST is just way to trick people into swallowing the pill.)
But would behavior change in the long run? Countries like Spain where solar noon differs wildly from clock noon just end up aligning their rituals accordingly (e.g. eating dinner at 9pm).
Yeah, it’s insane. Along with that, any permanent gains in the morning will be lost as soon as it becomes normal. Businesses will just open that much earlier. And this study assumed bedtimes of 10pm, which is not the average anywhere on the planet from what I remember the last time I looked into this. The average is like past midnight.
This just seems like a backwards justification. There is nothing wrong with a 9am sunrise or a 4:11am sunrise. People in Anchorage deal with both just fine.
> I am not awake at 4am, I have no use for sunlight at 4am
Most people aren’t awake at 5am either. Your use for the sun when there is an excess of it that goes well past your bedtime if you get up at 5am is irrelevant.
I can see the DST argument for people where the shift kinda sorta works out, but many places (like Anchorage!) it's completely unnecessary. I live in Sweden and it's just the twice annually "ah shit the clock moved overnight."
You realize that you can change your own sleep patterns seasonally if you want to? Heck, you could do that even gradually instead of those abrupt 1 hour changes. That is your choice, we don't need to fiddle with clocks for the whole society for that.
Between this and the "Sunset time and the economic effects of social jetlag: evidence from US time zone borders" paper [0], it seems like the issue is the size of the discontinuous jump in time, not necessarily that we change the clocks. So why not "smear" the DST<=> ST transitions by having four half hour transitions, once each quarter?
> So why not "smear" the DST<=> ST transitions by having four half hour transitions, once each quarter?
Very easy answer: Because it's already painful twice a year, and that would be making it even worse.
That answer is similar to the one for questions like "why do we have wide time zones that are somewhat inaccurate, rather than setting every clock based on the exact position of that clock?".
I’d be okay with every day having a different # of seconds. That way we slowly adjust with no discontinuity, but the nominal start time of school/work stays the same.
While this feels would be a disaster for other reasons like: “How many seconds are in an hour?” -> “Depends, no one knows.” … that’s already the case with our existing leap seconds.
(This sounds like kicking the can down the road to me; making the maximum discrepancy a minute could take 50-100 years and then you need a leap-minute or equivalent).
No. But the Earth has sped up a bit, so they're less necessary than at some times in the past. And we're on schedule to change them to be some kind of bigger, yet-undecided adjustment (perhaps a whole minute) before the year 2035 comes to a close.
If we move to leap-minutes, the Earth will do whatever it does, and it is expected that we'll be able to run on atomic time for a period of decades or perhaps even a century before we need to make another adjustment like we've done with leap seconds in the past.
Please name some of these countries. Europe is stuck with this nonsense and there is no hope in sight despite yearly polls showing majority people being against it.
The intent of DST is to normalize variations in the time of sunrise between summer and winter.
Places closer to the equator have minimal variation in the time of sunrise between seasons. They don't need DST.
Higher latitudes have large variation (i.e. Seattle, where the time of sunrise shifts between 4am in summer to 8am in winter), so they benefit from DST or summer/winter hours.
DST is one of the simplest implementations of seasonal hours on a regional scale.
What people usually mean by abolishing DST is permanent summer hours. If your problem was sunrise timing, then problem solved - DST actually moves that earlier than you require twice a year for normal working hours (i.e. less sun in the evenings). Source: my own high latitude life.
Abolishing DST for permanent summer hours don't address the winter sunrise issue.
Under permanent DST, the sun rises around 9 AM in December in Seattle. That's far too late. I, and millions of other people, do not want to wake up 2 hours before sunrise and drive to work in the dark.
Under the current system (DST reverts back during winter), sunrise is shifted an hour earlier to around 8AM, which is manageable. I don't have to drive to work in the dark.
No, it is intended for a small band of places where the latitude is big enough to make winter and summer daytime length significantly different, but not so different that DST does nothing. In Sweden, with DST, the sunrise is at 4am in summer and 8am in winter. Just set it so noon is actually noon.
> In Sweden, with DST, the sunrise is at 4am in summer and 8am in winter.
In Sweden, in summer without DST, sunrise in Stockholm would happen ~2:30 AM. In the current system, with DST, sunrise happens around 3:30 AM, an improvement.
In winter, if Sweden kept permanent DST (which is what many advocate for), sunrise in December would happen at around 9:45 AM. In the current system (shifting time back during winter), it happens around 8:45 AM, a more reasonable time.
You realize you're literally proving my point?
> Just set it so noon is actually noon.
Pretty meaningless to advocate for this, then every longitude would have its own timezone, defeating the purpose of timezones.
No, that’s describing permanent DST, which was tried and failed, not lack of DST. Most people in the world live without DST and it’s fine. (The article also mentions this.)
Except it's not like Chesterton's fence, it was created at the edge of living memory for known reasons. If anything it's an example of the opposite effect, something like Chesterton's field, do we really need to build a wall here, it's been a field for a damn long time...
With DST, there are actually 2 new concepts: ambiguous time (if the clock rolls back) and invalid time (if the clock jumps forward).
Java and Ruby work differently. Java would simply round the invalid time to the closest valid time IIRC. Ruby would accurately raise the InvalidTime exception. Same behaviors for an ambiguous time.
Chile is actually the country that will cause tricky issue in a system because they adjust DST at midnight... so there is one day a year where its midnight is considered invalid time. If we are building a system that depends on a day's boundary, then we will encounter this nightmarish issue where one of the days must start at 1am instead of midnight.
I live in Western Australia. for 3 years we trialed DST from 2006 to 2009. It was a nightmare personally, I was a sysadmin at the time and enterprise management tools were expensive and crap so we had to roll out DST file changes across our fleet manually. And because the change to allow DST for our region was a rushed job we then had to roll back after the 3 year unsuccessful trial.
Honestly, it was super stressful at the time. And DST that doesn't exist doesn't bother you in the slightest. Every day ends and flows into the next like the last. But the stress of a clock change twice a year doesn't have to happen, it's a choice.
Obviously I would have forgotten most of this given the change was 20 years ago but IIRC DST config on Solaris at the time was statically coded. You could modify the timezone config as a hacky fix on Solaris 8 but the permanent fix involved recompiling zic.
Are you Yanks seriously not going to get this sorted out before winter? BC has moved - can at least the rest of Cascadia get their asses in gear? Come on, California, I do not want to be dealing with a north-south time zone difference with my coworkers
Yes, we won't. It turns out that we're way too terrible at being rational way too much of the time.
For DST in particular: Even discussions where the participants manage to form something resembling a quorum to stop changing the clocks twice every year somehow manage to unilaterally get sucked into a seemingly-inescapable quagmire of differing opinions, wherein: The decision of whether to use standard time and stick with it or to stick with DST instead becomes an intractable impasse.
Accordingly, nothing ever gets done.
I have every expectation that I will be dead and buried before this issue is resolved.
My controversial idea: midnight should be where current 4AM is because 04:00 is the lowest point of human circadian rhythm. Currently we have nonsense like "1AM is technically a part of the next day but for all practical purposes it's still the previous day". Also, 24h clock should be the standard so that we can avoid discussions "is 12AM noon or midnight".
I really don't want the sunrise time to be 5:00 in the morning and still not have any daylight to do errands after work. I don't care what the reasons are, but if seasons change the sunset time, what's so wrong with changing it a bit more?
> the researchers estimate that permanent standard time would result in some 300,000 fewer people having suffered from a stroke and result in 2.6 million fewer people having obesity
That 2.6 million people are obese because of a 1h shorter change night in one Sunday a year is an extraordinary claim. I would love to understand how they got to this result.
In the summer the suns up at 5 am. But at 5am I am asleep. I could get up earlier but that's pointless since school and work doesn't start until 8.30.
So in stead of having an hour of sunlight before school and work we all change our clocks to have an hour of extra sunlight in the evening in stead, which fits our cultural preference for social activities.
We could also, as you say, change every single sign, post and display of opening hours for every school, business and organisation at the same time to achieve the same effect.
But in the real world changing the clock is simpler.
Some jobs should run every day at 8 am (e.g. torn on the temporary speed limit on front of the school), vs tasks that should actually run every 24h (e.g. feed the bacteria in exact time intervals)
* If it's being run to scrap data from a source that's available at some time, adjust the job if the source changes its time.
* If it's being run "when its dark and no one is around" then it'll run at some part of the dark bit regardless of DST changes.
Have a look at the sunset/sunrise graph for northern parts of the US https://www.timeanddate.com/sun/usa/seattle
In Seattle, without DST, sunrise happens at 4:11am. Because of DST, it's pushed back an hour later to a more reasonable 5:11am.
I am not awake at 4am, I have no use for sunlight at 4am, and I don't want the sun appearing that early. That hour of early sunlight is wasted for me. Plus with DST, the sun sets an hour later, at 9:11pm, a time I am actually awake, and I can actually go outside and use the extra sun.
And, with permanent DST (which is what many people are advocating for), then in winter sunrise is at 9am in Seattle, which is far too late. I do not want to drive to work in the dark, before sunrise. So I want standard time in winter, pushing sunrise an hour earlier to a more reasonable 8am.
In both situations (summer and winter), modifying the time via DST benefits me and gives me better use of sunlight.
If your issue is when work is scheduled, well businesses set their own hours, not the government.
> If your issue is when work is scheduled, well businesses set their own hours, not the government.
Ah, someone who doesn't have kids in school/camp/some random activity yet.
We know how this goes in China (one time zone, no daylight savings time). Coming home from the bar in Beijing with the sun showing up at 4 AM was quaint back then, but I'm definitely glad we have DST in the states.
I think the talk of daylight savings time is a distraction, in the end it is arbitrary what the clock says. As a society we need to negotiate when (in celestial time) we want to do certain activities. For example, there are a lot of studies that school starts to early (relative to sunrise and the average bed time of teenagers). But the school starting time has to be decided politically. And reduced working hours or later start times have to be negotiated by trade unions, politics etc.. That's a lot more messy than just shifting wall time.
Our school schedules are set by weird rules involving when school bus capacity is available. But in general, 9AM is about when school starts (for my son's K-8, its 8AM here for K-5s), or summer camp session starts, or whatever. My schedule is so influenced by my kid these days, it happens to correspond to rush hour, which sucks, because everyone else's schedules are intertwined (so traffic).
I WFH and can definitely set my own work hours. Which is why its 12:30 AM and I still haven't gone to bed yet.
I will fight tooth and nail against attempts to take one hour of daylight from me in the evenings for half of the year.
The bar near me has different opening hours to the library, and that has nothing to do with DST.
In plenty of countries the government decides the opening hours of shops, restaurants and sometimes even offices. Labour laws and nighttime pay are coupled to the hours on the clock. Hours you can make noise is decided by government. Germany has the mid-day resting hour (Mittagsruhe).
Parts of Vermont have traditionally coped with this by having an 8-4 workday instead of 9-5.
But the reality is that Vermont gets only about an hour of daylight outside working hours, depending on local customs. People have extremely strong preferences about how that hour gets split up.
But would behavior change in the long run? Countries like Spain where solar noon differs wildly from clock noon just end up aligning their rituals accordingly (e.g. eating dinner at 9pm).
> I am not awake at 4am, I have no use for sunlight at 4am
Most people aren’t awake at 5am either. Your use for the sun when there is an excess of it that goes well past your bedtime if you get up at 5am is irrelevant.
Under DST, at summer solstice, the sun rises around 5am, giving me 2 hours of wasted sunlight.
Without DST, at summer solstice, the sun rises around 4am, giving me 3 hours of wasted sunlight.
I enjoy having additional hours of sunlight when I am awake, so for me I actually prefer having DST vs without it.
Similarly, in the wintertime, under permanent DST, sunrise is around 9am, and I don't want to drive to work in the dark.
It's not like without DST you have to work so late that you don't have enough hours for sleep, right?
[0]https://pubmed.ncbi.nlm.nih.gov/31030116/
Very easy answer: Because it's already painful twice a year, and that would be making it even worse.
That answer is similar to the one for questions like "why do we have wide time zones that are somewhat inaccurate, rather than setting every clock based on the exact position of that clock?".
While this feels would be a disaster for other reasons like: “How many seconds are in an hour?” -> “Depends, no one knows.” … that’s already the case with our existing leap seconds.
Which we are also in the process of getting rid of.
(This sounds like kicking the can down the road to me; making the maximum discrepancy a minute could take 50-100 years and then you need a leap-minute or equivalent).
If we move to leap-minutes, the Earth will do whatever it does, and it is expected that we'll be able to run on atomic time for a period of decades or perhaps even a century before we need to make another adjustment like we've done with leap seconds in the past.
https://en.wikipedia.org/wiki/Leap_second#Phase-out_and_futu...
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edit: Yeah, I see that your edit covered this adequately. No worries. :)
To that end, I'd like to propose 12 transitions. These should happen on the 16th day of every month, at precisely 05:14:33.
Let's take our seasonality more seriously.
According to https://en.wikipedia.org/wiki/Daylight_saving_time_by_countr... since 2000:
Queensland Australia is relatively close to the equator, and the length of day does not change dramatically between summer and winter.
DST is intended for places at higher latitudes.
The intent of DST is to normalize variations in the time of sunrise between summer and winter.
Places closer to the equator have minimal variation in the time of sunrise between seasons. They don't need DST.
Higher latitudes have large variation (i.e. Seattle, where the time of sunrise shifts between 4am in summer to 8am in winter), so they benefit from DST or summer/winter hours.
DST is one of the simplest implementations of seasonal hours on a regional scale.
Under permanent DST, the sun rises around 9 AM in December in Seattle. That's far too late. I, and millions of other people, do not want to wake up 2 hours before sunrise and drive to work in the dark.
Under the current system (DST reverts back during winter), sunrise is shifted an hour earlier to around 8AM, which is manageable. I don't have to drive to work in the dark.
https://www.timeanddate.com/sun/usa/seattle
It can be dark in Brisbane and still light at my parents house near cape york.
In Sweden, in summer without DST, sunrise in Stockholm would happen ~2:30 AM. In the current system, with DST, sunrise happens around 3:30 AM, an improvement.
In winter, if Sweden kept permanent DST (which is what many advocate for), sunrise in December would happen at around 9:45 AM. In the current system (shifting time back during winter), it happens around 8:45 AM, a more reasonable time.
You realize you're literally proving my point?
> Just set it so noon is actually noon.
Pretty meaningless to advocate for this, then every longitude would have its own timezone, defeating the purpose of timezones.
Did they get several cities to participate?
https://en.wikipedia.org/wiki/Permanent_time_observation_in_...
Possibly another example of the old Chesterton's Fence.
Java and Ruby work differently. Java would simply round the invalid time to the closest valid time IIRC. Ruby would accurately raise the InvalidTime exception. Same behaviors for an ambiguous time.
Chile is actually the country that will cause tricky issue in a system because they adjust DST at midnight... so there is one day a year where its midnight is considered invalid time. If we are building a system that depends on a day's boundary, then we will encounter this nightmarish issue where one of the days must start at 1am instead of midnight.
I really hope DST is going away soon.
Honestly, it was super stressful at the time. And DST that doesn't exist doesn't bother you in the slightest. Every day ends and flows into the next like the last. But the stress of a clock change twice a year doesn't have to happen, it's a choice.
(Sorry about your nightmare. It was easy on the systems I took care of at that time.)
For DST in particular: Even discussions where the participants manage to form something resembling a quorum to stop changing the clocks twice every year somehow manage to unilaterally get sucked into a seemingly-inescapable quagmire of differing opinions, wherein: The decision of whether to use standard time and stick with it or to stick with DST instead becomes an intractable impasse.
Accordingly, nothing ever gets done.
I have every expectation that I will be dead and buried before this issue is resolved.
That 2.6 million people are obese because of a 1h shorter change night in one Sunday a year is an extraordinary claim. I would love to understand how they got to this result.