Twice a year there's a flurry of comments, opinions, and just plain whining about how much better life would be if we just stayed on daylight time all the time. It's a debate that I'm unable to stay out of, but I'm tired of retyping the same stuff each year. I'm not sure why I do this to myself, as I do okay in either Eastern Standard Time or Eastern Daylight Time.
The big event in the arena is that the senate unanimously passed S. 623, the Sunshine Protection Act of 2021 on 2022 March 15. There is a clause that lets states that currently use full time standard time to remain there, for everyone else, the current Daylight Saving Time becomes the new Standard Time. Before that bill, some 18 states have passed bills or referenda calling for adoption of full time daylight saving time or moving into the time zone east of their current zone.
It's well past time to collect all the pros and cons in one spot. Note that one person's pro is someone else's con, and one person's con is someone elses pro. So let's just call them issues. I have my biases, but I'll also try to be fair. After all, astrologers say I'm a Libra (the scale) so that's influenced me to be fair and balanced - and that's about the only thing about astrology I accept.
I'm going to be using some abbreviations. Most are obvious, some are just shorthand:
EST: Eastern Standard Time, also CST, MST, PDT, AKST, and HST.
EDT: Eastern Daylight Time, also CDT, MDT, PDT, and AKDT. And HDT, which doesn't really exist.
DST: Daylight Saving Time. Not Savings, just Saving.
FTDST: Full Time Daylight Saving Time, or permanent DST, but I doubt it will be permanent.
Back before we had clocks and travel was on foot or horseback (i.e. horse foot), three important points in the day were sunrise, noon, and sunset. Noon is a good focus. Back then noon was when the sun reached the highest point in the sky. "High noon" might reinforce that concept. These days astronomers and others call it "local noon," not to be confused with "local mean noon" which can be ±15 minutes earlier or later. The hottest part of the summer day generally doesn't occur until a few hours later, call it siesta time, but I won't have more to say about that.
A very useful aspect to local noon is that the shadow from a (vertical) flag pole points due north or due south on a flat surface. That's always north in our northern temperate zone and Arctic, always south in the southern temperate zone and Antarctic, sometimes north, south, or overhead in the tropics, and the North Pole and South Pole are curious exceptions.
As people managed to build accurate clocks they discovered that the time from one noon to another generally wasn't quite 24 hours. This likely led to people claiming their sundials kept better time than those newfangled clocks. The difference turns out to be a combined effect of the Earth's slightly elliptical orbit and it axial tilt that bring us our seasons. Clock makers and astronomers managed to come up with a scheme where their clocks' noons averaged out to 12 PM and named it "local mean time." The difference between local time and local mean time is called the Equation of Time. The Old Farmer's Almanac refers to it as "Sun Fast" and "Sun Slow."
The net effect is small enough to have little impact on the Daylight Time debate, but it intrudes once in a while.
As timepieces improved and railroads spread across continents, local mean time interfered things like train schedules. You could take a three hour train trip west and your pocket watch would be wrong at the destination. In 1878, Canadian Sir Sandford Fleming proposed the idea of creating 24 standardized time zones. They were patterned on bands of longitude 15° wide where the center's local mean noon matched clock time across the entire zone. Instead of being absolute 15° bands, the borders follow convenient political and physical boundaries. United State railroads adopted the scheme merely five years later.
In 1895, George Hudson, an entomologist from New Zealand, came up with the concept of daylight saving time. He wanted more time after work to go bug hunting in the summer. In England, William Willett advocated for the concept (he called it summer time) starting in 1905, but ultimately it was Germany in 1916 that was the first to adopt it to divert fuel from lighting to World War I. Other countries followed suit, but then dropped it later. Franklin Roosevelt adopted it as "War Time" from 1942-1945 and many states continued to use it in the summer. In January 1974 the US switched to daylight time in response to the Arab oil embargo, but abandoned the plan before the regular October change.
The reasons for or against daylight time are, not surprisingly, very location dependent. Hawaii is close to the tropics, they don't use daylight time. The southernmost Aleutian Island in Alaska is at 51°N. Scandinavian countries are further north, I assume they use daylight time to stay in sync with their neighbors. A notable exception is Iceland, but it doesn't have neighbors.
Here's a handful of cities, their location, timezone, sunrise and sunset around December 21st if they used daylight time, and the length of daylight then.
City Time zone Lat / Long Sunrise Sunset Daylight Notes Honolulu HI HDT 21.3° / 157.9° 8:05 AM 6:55 PM 10h50m Hawaii is really full time standard time Fairbanks AK AKDT 64.8° / 147.7° 11:58 AM 3:40 PM 3h43m The other US state extreme Seattle WA PDT 47.6° / 122.3° 8:55 AM 5:20 PM 8h25m High latitude San Francisco CA PDT 37.8° / 122.4° 8:22 AM 5:54 PM 9h32m Nearly due south of Seattle Minneapolis MN CDT 45.0° / 93.3° 8:49 AM 5:34 PM 8h46m Moderately high latitude New Orleans LA CDT 30.0° / 90.1° 7:52 AM 6:05 PM 10h13m Center of time zone Chicago IL CDT 41.9° / 87.6° 8:15 AM 5:22 PM 9h07m East of center of time zone Indianapolis IN EDT 39.8° / 86.1° 9:02 AM 6:23 PM 9h21m Near Chicago, way west of center New York NY EDT 40.7° / 74.1° 8:17 AM 5:32 PM 9h15m East coast megalopolis Miami FL EDT 25.8° / 80.2° 8:03 AM 6:35 PM 10h31m Southernmost example Eastport ME EDT 43.0° / 71.9° 8:16 AM 5:16 PM 9h00m Easternmost city in the US
Daylight Saving Time serves various purposes, from the best known ones to lesser ones like saving energy and chasing insects in the evening. There are several more, some are described below. Let me know others I should include. Each has fans and detractors, most have several aspects that need consideration, and that's what I really want to convey on this web page. Let me know what I've missed. One aspect that likely touches all the issues is selfishness - pretty much everyone has personal reasons to support or oppose issues important to themselves. However, most people assume that their desires mesh with everyone else's in the time zone, or at least their state. Some of these people are very vocal and ignore the voice of reason. (Even my voice - can you believe that? Imagine a smiley face emoji here.)
First, I was going to call this an issue, but it doesn't really fit all that well. The whole concept of daylight time could just go away if employers used seasonal schedules for their stores, offices, factories, and schools. Some already do that, e.g. vacation areas like beaches and ski areas. If everyone used their own schedules, things would be even more confusing and annoying than they are now.
I like to call DST the quintessential kludge, a term embraced in the computer industry's hardware and software camps. The original Jargon File defines it best:
KLUGE (kloodj) alt. KLUDGE [from the German "kluge", clever] n. 1. A Rube Goldberg device in hardware or software. 2. A clever programming trick intended to solve a particular nasty case in an efficient, if not clear, manner. Often used to repair bugs. Often verges on being a crock. 3. Something that works for the wrong reason. ...
(Aside - I learned "kludge" when I was at Carnegie Mellon Univ. and have never warmed up to kluge. Sorry. [Not very.])
Instead of trying to get everyone to change schedule, a government law that forces everyone to adopt a new schedule without having to update signage, web pages, etc. works great - but annoys everyone for other reasons. The urge to write this WWW page annoys me!
Ultimately, the problem boils down to the tilt of the Earth's axis. Assuming that we won't have the means to fix that in our lifetimes, we'll have these issues.
This truism isn't 100% true, and represents some selfishness (remember - all these do). Let's put this on hold for a bit....
Why? Some "early birds" do like seeing dawn, especially on the east coast. Some even take sunrise photos that would be nice to see in person. I'm a bit of an amateur astronomer - some comets are only visible before dawn. I'm more in the "night owl" camp. Whenever I have to get up at 5 AM to be on the road to catch a morning airplane flight I'm amazed at how many people got to the road before me. Here in the northeast (I'm in NH, 3° east of the astronomical center of the eastern time zone) sunrise in EST ranges between 4:07 and 7:20 AM. Dealing with 9 to 15 hours of daytime really is difficult at these latitudes. One could argue that people in the northeast aren't willing to doing tasks a like weeding the garden before going to a 9-5 job. Farmers and construction workers are willing to start early and get an extra hour or two in the afternoon.
One topic that deserves a separate web page is that people have a very pronounced circadian clock. It deserves a separate web page, and is something I've acted on, but here it suffices to say most people may "free run" expecting a day to be about 24.9 hours. This was discovered by experiments with people living in caves and letting them eat, sleep, work etc when they feel like it. In real life, that morning sunlight sends a signal to your hypothalamus skip that extra 0.9 hour to resync with our 24 hour days.
One application of this is the bright lights that people with Seasonal Affective Disorder use in the morning.
I suspect it's also one reason why there are so many "night owls." It may also be why the early birds always seem to be yammering about how pretty the sunrise was and how they had the whole beach to themselves. Instead of FTDST, perhaps people should sleep in east facing bedrooms. And go to bed earlier. Keep it in mind.
On FTDST, sunrise for me would be 5:07 to 8:20 AM. That 8:20 AM could be a big problem, I'll go into that in later issues.
Umm, where was I? Oh, on FTDST sunset would range from 5:12 to 8:30 PM for me. Somehow, that seems like a smaller range than sunrise. People at 9-5 jobs would be driving home in December during twilight. Maybe that's better than full darkness, but New Englanders won't be enjoying evening sunlight. Maybe in February. Over in Indianapolis, their 6:23 PM sunset might work well when coupled with a late dinner.
I'm not convinced that extra hour before sunset is all that useful.
There's a whole bunch of aspects to this issue.
One application of this is the bright lights that people with Seasonal Affective Disorder use in the morning.
People often report it's difficult to get on to the DST schedule. Potential reasons include:
Jumping 1.9 hours instead of that 0.9 hours we usually do.
There's less sunlight in the morning.
There are studies that show there's an increase in heart attacks, car crashes, and other unhealthy events early in DST.
These are presented as reasons for FTDST. However, the later sunrises throughout the winter suggest we may be trading a few days of inconvenience for a full winter of difficulty getting going in the morning, especially in the western part of time zones.
Some sleep researchers use this as an argument that we should stay on Standard Time throughout the year and completely ditch DST. Be careful what you wish for - you may get it.
This paragraph is "Just kidding." Given that a one hour time shift is so bad for us, shouldn't our Nanny State Government, which has our best interests at heart, apply this knowledge to the effects of jet-lag? In particular, they should limit all east-west travel to not more than 5° of longitude, about 300 miles at my latitude. This would mean shifts of 20 minutes per day, certainly that would be much better for us than the three hour shifts when we fly across the country. Perhaps there could be an exception for cargo pilots, as they are trained professionals and know how to cope with jet lag. Congress could wax ecstatic about it as an infrastructure/jobs program because regional airports will need to be enlarged and new hotels will have to be built.
Yesterday I stumbled across a paper that reports worsening cancer rates within time zones. I haven't read it closely yet, but if this is true, then FTDST likely makes things worse! The sleep research folks will likely be all over it. The increase varies with the type of cancer, but overall, it looks like there's a 10% increase between the eastern edge and western edge. The paper did not break diagnoses down by season or month. Given the long lead time for cancer development, it may be difficult to analyze that. And, of course, the study doesn't provide an explanation. It could be simply that more people cook over charcoal grills given the later daylight and warmer temperatures of the current DST.
From the Abstract:
Results: Risk increased from east to west within a time zone for total and for many specific cancers, including chronic lymphocytic leukemia (both genders) and cancers of the stomach, liver, prostate, and non-Hodgkin lymphoma in men and cancers of the esophagus, colorectum, lung, breast, and corpus uteri in women.
Conclusions: Risk increased from the east to the west in a time zone for total and many specific cancers, in accord with the circadian disruption hypothesis. Replications in analytic epidemiological studies are warranted.
Impact: Our findings suggest that circadian disruption may not be a rare phenomenon affecting only shift workers, but is widespread in the general population with broader implications for public health than generally appreciated.
Yes, I'm old enough to remember some history. I lived in Pittsburgh PA in early 1974 while the Arab oil embargo made finding gas challenging. In order to reduce oil consumption, Congress put the US on FTDST as of 1974 Jan 6. The next few issues mention some results. The New York Times reported that in October, Congress decided to return to Standard Time between Nov 27 and Feb 23. The year after that we went back to the previous transition in April.
A study on public acceptance of daylight saving time was conducted by the National Opinion Research Center of the University of Chicago and showed that 79 per cent of those interviewed last December favored the daylight time move. This total dropped to 42 per cent in February.
I could argue about the crisis, but won't on this page. As for saving oil, the NY Times article said we didn't save much:
The Senate Commerce Committee estimated that the nation saved 100,300 barrels of oil daily in the January through April period by use of daylight saving time. It also noted "a majority of the public's distaste" for daylight time during the darkest and coldest winter months.
As for saving electricity, things are also unclear. The National Bureau of Economic Research looked at Indiana's experience when counties in the state that used only Standard Time changed to DST rules in 2007. They discovered that DST increased electricity use and summarized with:
DST causes the greatest increase in electricity consumption in the fall, when estimates range between 2 and 4 percent. These findings are consistent with simulation results that point to a trade off between reducing demand for lighting and increasing demand for heating and cooling. We estimate a cost of increased electricity bills to Indiana households of $9 million per year. We also estimate social costs of increased pollution emissions that range from $1.7 to $5.5 million per year. Finally, we argue that the effect is likely to be even stronger in other regions of the United States.
They conclude that an individual ratepayer might pay "an average of $3.29 per year in increased electricity bills."
Let's call this issue a non-issue.
This is the final lesson from history. This claim was one argument against the 1974 change in the Pittsburgh area. DST resumed in January, but it wasn't until February that the first fatality made the news. I can't find a reference to that, but I've seen reports of problems from the Washington DC area and even central Florida.
Some recent research shows adolescent kids tire later at night and hence should start school later. I don't quite understand the science behind it (see References), some school systems have started high school later and report good results. What happens with FTDST? Should school start even later to provide daylight before school? Daylight still seems important to keep the kids on schedule.
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One thing I came across while looking into FTDST is that there are several countries that adopted some form of DST but have have dropped the concept. Timeanddate.com goes into gory detail, but of 143 countries that have tried DST, only 74 still do, mostly the Mexico, USA, Canada, and Europe. Russia ended DST in 2010. Most countries in South America have tried it, but only a few still use it. The EU is considering ending their DST, but handling Covid-19 has pushed that aside for now. |
To get a better handle on the effects of daylight and standard time around the country, here are a couple sites with maps or satire to explore.
Andy Woodruff's Daylight Saving Time Gripe Assistant Tool will give you an interactive summary about days with annoying times for sunrise and sunset over a full year given whether or not DST is used full time, as now, and never.
The Washington Post's How permanent daylight saving time would change sunrise and sunset times article has a good map showing the latest sunrise time in DST terms. It also has an animation showing how it changes over a year.
If you heard that a Ben Franklin Invented Daylight Saving Time, your source is misinformed. However, he did suggest that Parisians could save candles by awakening early with the sun:
Your readers, who with me have never seen any sign of sunshine before noon, and seldom regard the astronomical part of the almanac, will be as much astonished as I was, when they hear of his rising so early; and especially when I assure them, that he gives light as soon as he rises. I am convinced of this. I am certain of my fact. One cannot be more certain of any fact. I saw it with my own eyes.
…
Every morning, as soon as the sun rises, let all the bells in every church be set ringing; and if that is not sufficient? Let cannon be fired in every street, to wake the sluggards effectually, and make them open their eyes to see their true interest.
I'm happy with the status quo, though we may have stretched out DST too much with the March/November transition dates adopted in 2007. My 2003 weather station is too old to have updateable firmware, so it's permanently on the old scheme. It does have a manual mode, so I use that. I am enough of an amateur astronomer to prefer that local noon occur close to 12 PM, so instead of FTDST I'd prefer staying on standard time and shift work and school hours earlier. I do like seasons, and do like the the latitude I'm in so don't expect to see me move south for the smaller swing between sunrise and sunset.
I do expect that if the states that claim they want FTDST get their wish, most will soon discover they were better off before. As for people who have trouble with the transition to DST, I think they should try shifting their bedtimes 10 or 20 minutes a day instead of making the full hour shift on a Sunday.
These are various sources I found but generally didn't link to above. Some are more technical than the links above, but go into more details than I did. Some of these are maps by
https://twitter.com/Climatologist49
Brian Brettschneider makes some really neat maps, I need to get in touch and get permission to
use them.
https://pbs.twimg.com/media/DuE-S5IUwAAOYiI?format=jpg
Map of the earliest sunset times in the USA and Canada.
https://pbs.twimg.com/media/Cz15K7iVEAQOhWu?format=jpg
Hours of daylight on winter solstice
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6751071/
Effects of light on human circadian rhythms, sleep and mood
https://jcsm.aasm.org/doi/10.5664/jcsm.8780
Daylight saving time: an American Academy of Sleep Medicine position statement
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.490.7167&rep=rep1&type=pdf
Sleep, circadian rhythms, and delayed phase in adolescence
https://www.sciencenews.org/article/daylight-saving-time-sleep-health-science
A Nov 2022 article that came out after I wrote this page. It centers mainly on sunlit mornings and school children. "Our once testy tween zombie is now ... moderately awake and relatively lucid."
https://aacrjournals.org/cebp/article/26/8/1306/283057/Longitude-Position-in-a-Time-Zone-and-Cancer-Risk
Longitude Position in a Time Zone and Cancer Risk in the United States
https://www.timeanddate.com/news/time/us-permanent-dst.html
US Senate Approves Permanent DST Bill
https://www.congress.gov/bill/117th-congress/senate-bill/623/text
S. 623: AN ACT: To make daylight saving time permanent, and for other purposes
This is mainly for my use as a handy source for URLs to the individual issues. I want to be able to plop them in FaceBook comments instead of retyping yet another comment on an issue.
Contact Ric Werme or return to his home page.
Written 2022 Mar 20, last updated 2023 Mar 7.