Daylight Saving Time

Change your clock twice a year by an hour. Apparently, those that venture outside and are slaves to the NineToFive routine get more sunlight this way. The rest of us just get headaches from it.

Worst idea ever. Marginally worse than TimeZones.

The idea behind DST is to make people get up an hour earlier. That is all fine and well, but it doesn't really save anything, it just moves one of the dark(ish) hours from afternoon to morning. -- OleAndersen

Quoth SunirShah on TimeZones: P.S. If I were smart, I would have gone on Google in the first place:

To see who uses it:

DaylightSavingTime is favored by... It is fought by...

UK report

The UK changes back to GMT in just under two weeks. Your reporter here wonders: could Wiki do what all other methods have failed to do thus far - tell me when every other part of the world, especially bits of North America, shift by an hour also? (The southern hemisphere seems to go in the opposite direction, I have begun to realize over the years.)

IIRC, the EU countries now have their daylight saving time synchronized. October 29th is the day when we all go 1 hour back. Always on a Sunday, to give people another day to make the switch.

However, not all EU countries are in the same timezone. Some folks would like to see the UK move to GMT+1 in the winter, with "double summer time" in the summer. Thus the London banks would get to be in the time zone appropriate for Vienna. And everyone in Scotland would get to go to work in the dark all year.

The idea of daylight saving was first mentioned in a whimsical essay by BenjaminFranklin in 1784, titled "Turkey vs Eagle, McCauley? is my Beagle."

It was first advocated seriously by a London builder, William Willett (1865-1915), in the pamphlet "Waste of Daylight" (1907) that proposed advancing clocks 20 minutes on each of four Sundays in April, and retarding them by the same amount on four Sundays in September. As he was taking an early morning a ride through Petts Wood (in north-west Kent), Willett was struck by the fact that the blinds of nearby houses were closed, even though the sun was fully risen. When questioned as to why he didn't simply get up an hour earlier, Willett replied with typical British humor, "What?" In his pamphlet "The Waste of Daylight" he wrote:

Everyone appreciates the long, light evenings. Everyone laments their shortage as Autumn approaches; and everyone has given utterance to regret that the clear, bright light of an early morning during Spring and Summer months is so seldom seen or used.

I think it is more about changing at a time when a minimal number of people is active. Think of the chaos that would break out if we switched in the middle of rush hour... -- OleAndersen

Generally in the USA, the transition from Standard time to Daylight time happens on the first Sunday in April. On that day, at 2:00am, it becomes 3:00am. The transition from Daylight time back to Standard time happens on the last Sunday in October. On that day, at 2:00am, it becomes 1:00am (for the second time that day :-). There is a saying here to help folks remember the time change direction "Spring forward, fall back."

This doesn't apply to everywhere in the US - I think Arizona does not have Daylight Saving Time (although some Native American Reservations there do). Anyone got more info on exceptional cases in the USA?

Arizona doesn't have daylight saving time because we tried it, and didn't like it.

Arizona really needs to observe DST during the summer between April and October. To assure that they'll have a good taste of having daylight/twilight later in the evening if the government allow to use DST which means still on the MST. However, since Arizona does not observe DST, which means they are on California time (PST), it gets dark early and California still has daylight a little while longer. If Arizonas were smart enough, they could tell the local government to move the clock 1 hour forward and still be on MST, not on PST. The Indian Reservations do observe daylight savings; they are on MST while the rest of the state is on PST. You may want to check on and most of USA have daylight after 8pm. Best if the people in the state of Arizona to persuade the government or vote.

Can someone improve the wording of the above paragraph, please? I've worked on it a bit. :-|

Indiana finally observes Daylight Saving Time throughout the entire state after decades of having only parts of the state doing so. A friend of mine told me that the original problem was a struggle between broadcasters, who wanted to be in daylight time so their shows would air at the announced times for the rest of the country, and drive-in movie operators, who preferred the earlier sundown of standard time. I can't guarantee that story is true.

Hawaii does not have daylight time either.

-- RobertField

Having lived in Hawaii for three months in the winter of 1999-2000, I can authoritatively state that sitting at a latitude of roughly 20degrees N of the equator, Hawaii needs DST even less than the rest of the US. Because of course, at that latitude, the length of the day doesn't vary much. -- StevenNewton

I heard that farmers don't like Daylight Saving Time because it "upsets the milk cows" to be milked an hour earlier or later in the morning. My response is "take the clocks out of the barn." ;->

(Actually, the cows get uppity because the farmer's children, who must leave for school an hour earlier or later, do their chores an hour off, and that bothers the cows.) -- JeffGrigg

I thought that the whole reason for daylight savings time was for the farming community. That the extra hour of light in the morning helps in farming and ranching. Was I given the wrong information?

That was the impression I was under too. Looks like someone really messed this one up. -- MatthewTheobalds

In the UK, the needs of farmers are the normal reason given for BST. It makes no more or less sense than any other stupid excuse.

In situations where milk cows could get themselves milked whenever they felt like (e.g., by using robotic milking sheds), it's been noticed that they often tend to wander in around midnight to get milked - and spend the dawn hours sleeping. The only reason why dawn milkings are traditional is because the farmer couldn't be persuaded to get out of bed any sooner and the cows have come to expect it.

So how can we undo this mess?

Civil disobedience! I refuse to set my clock back an hour next Sunday. Who's with me?

That would, of course, get you stuck in the wrong time zone.

I have been doing this for about 6 or 7 years. All my clocks, watches, telephones etc. stay on GMT all year round. I recommend it. It's not as much of a problem as you might expect - you just have to mention it or convert when you communicate times to other people. Most of them think I'm insane, but it makes the point, and many of them would probably think I'm insane anyway. -- AndrewMcGuinness

Stop the earth from rotating. This will, of course, precipitate the end of the world. The book SignalToNoise by EricNylund makes heavy use of that fact.


Advantages: daylight savings for Amtrak, Airlines, Freight trains, other transportations, sports including Arizona Diamondbacks.

The heat will not make any difference during the summer. Texas heat remains hot and the state observes DST and so does New Mexico.

Farmers hate daylight savings and they try to activate people's lives.

--- DST can also lead to bugs in several types of programs. For example, let's say you have a very simple data aquisition program that logs time and dates along with a measured value and then writes that to a file. What happens as soon as the clocks are set back? Well, you then have two sets of data overlapping a single hour. This esentially destroys two hours worth of data because there is no way to distinguish between the two hours unless you actually planned for this in the software upfront. The best solution of course is to stick with UTC and not worry about timezones or DST at all.

The latest troubles with DaylightSavingTime were reported 2003 from eBay: (in german)

See Also: DateAndTime

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