There's a lot of talk about acute risks--what happens a day or two after the time change. Most articles you'll read are all about this.
The second topic, the main one that circadian scientists talk about, is chronic risks, and I believe they are more important to our health. To follow this logic, you have to believe that people will continue doing whatever it is they do today (e.g., going to bed at midnight), and won't shift their schedule around right away to optimize sleep--i.e. they will not recognize that their body clock is set mainly by sunlight. The campaign to change school start times has been going for 25+ years already, so fast changes here are pretty rare.
When the clocks change, people wake up at a different circadian time, and if that time is too early, it is associated with worse health outcomes.
Some large-scale epidemiological tools have been used to figure these things out. One compares the difference between sleep patterns on "work" days and "free" days - like how much do you sleep in on a weekend? (Till Roenneberg's "social jetlag"). A second method uses "position in timezone" - comparing people living on the eastern or western edge of a timezone in various ways.
Roenneberg's work from the mid-2000s showed that night owls suffer a lot under "wake up before the sun" kinds of schedules (their "social jetlag" is bigger) - it makes them fatter, more irritable, get more diabetes, etc. They don't go to bed any earlier, but they're forced to wake up earlier.
Next, when you look at timezone position (this has been done for millions of people), people on the western edge of a timezone (where the sun comes up later but the clock is set at the same time) are quite a bit worse off for cancer rates and obesity - 10-20% more for some kinds of cancers, and a roughly 20% increase in chances of being obese.
I work third shift, but switch to daylight schedules on weekends and trips often. I've just learned to plan my sleep about 24-36 hours in advance, and do anything necessary to ensure I get sufficient sleep before any planned activity (workout/stay up late/sleep short amounts to induce sleepiness at the correct time to get a good, long sleep before engagements). I'm pretty independent of circadian rhythm now. As a side effect, as someone who used to consider themselves a night owl, I now prefer to wake up around sunrise whenever possible (assuming I'll be able to do it for a few days in a row)
It's not like jet lag is a new phenomenon. It's just a bit unfortunate to introduce minor jet lag to the entire population without giving them much chance to adapt.
Yes China should have some of this, but they have also had time to adapt to a fixed timezone.
Most of these curves are U-shaped...
I think generally standard time-1 would "hurt" early birds, and DST/double DST would discriminate against night owls.
The pattern for early birds is they get an invite for a business dinner at 9PM (staying up late) and then they wake up at 4:30AM anyway, so they don't sleep enough when you make them stay up late.
Good reasons, for sure. And engineers want to stop changing clocks twice a year for other good reasons. And many laypeople want to stop changing clocks twice a year because it's bothersome and tiresome. I don't particularly care which time zone is ultimately selected for my state; I just want it to be fixed year-round.
Perhaps obvious but have you tried sleeping in pitch black and/or with eye cover? If you need natural light to wake up you might be able to sleep very well in the dark and mimic it with an ambient light alarm clock
I used to think that but then I realized that you would also have some parts of the world where the date switches over in the middle of the day. I mean it is certainly odd that different parts of the world are on a different day than other parts, but I think switching the date in the middle of the day is a bigger issue.
Is it a bigger issue than signing and dating a document while in a different time zone from the one the document needs to be dated in? E.g. signing a contract on the west coast when the contract needs to be dated on eastern time because of regulation X by agency Y. What if there are multiple regulatory agencies that want you to date the document in different time zones? e.g. the SEC and the ECB.
I would argue it makes the most sense to date all legal documents in UTC and using any other timezone would be a confusing mistake. But we can disagree.
For America, maybe EST sure, but UTC would not make any sense. Most people do not have an intuitive understanding of what their time zone to UTC is. However, picking a single well defined timezone would still fit your intent.
UTC every where is only good for lazy developers. The benefits to having a general idea globally when the sun rises and sets, when people aren't working, when stores and restaurants are open, etc immediately is so beneficial
It's not just good for developers. Coordinating any plans across timezones always requires the timezone to be explicit, one universal timezone doesn't. It wouldn't be hard at all for people to get accustomed to the numbers associated with their local daylight cycle, and travellers can use a phone or website to lookup sunrise/sunset in any location, as is already possible.
Maybe we could even eliminate hours and minutes and just use percents and thousandths of a percent of a day (14.4 minutes and 864 ms respectively), to avoid factors of 60 or 24 or 3600 or 1440.
So basically in order to coordinate activities across time zones (rare), you give up having a common rough time system for waking, eating, shopping, etc. And as you said, users can “look up” their time relative to the normal on a website, which means that now people have time zones, just without any of the benefits.
Everyone has a smartphone these days. There should be fifty time zones in the US, and your smartphones should adjust the time by a few minutes every night so that sunrise is always at 7 am, which mimics what would occur naturally. When you want to know the time elsewhere, you ask Siri. That should make humans much healthier by keeping circadian rhythms naturally aligned, not under continuous stress from artificial UTC, or even DST.
Only 50? The country spans almost 110° longitude, from West Quoddy Head lighthouse in Maine (66 degrees 57 minutes west.) to Cape Wrangell on Attu Island, Alaska (172 degrees 27 minutes east.)
That's nearly 1/3 of the globe. So why not ~450 down-to-the-minute timezones? Or, why not subdivide those into 28,000 down-to-the second timezones?
How would we ever ensure that all those times were universally coordinated?
Optimal and ideal for whom? Utc is horrible for anyone who travels or deals with people outside the timezone.
What do people in China think of one gigantic timezone?
>Utc is horrible for anyone who travels or deals with people outside the timezone
What no. Those are the situations where variable timezones are the most annoying because that's when you have to do the most timezone converting. Frequent ambiguity as to which 9pm, having to do math to resolve it in to a time that makes sense relative to you, and that's if it's expressed in a way that lets you do so ie "UTC+2" but more often than not they say "Eastern European Time" like that clears it up for anyone who isn't their next door neighbour. You shouldn't have to turn to google to work out what time someone is trying to say.
The title here implies that there's a consensus among "health experts", but there is no such thing. Click bait. All we have is some health experts saying there are downsides to the back and forth switch
I think the point is there are health experts who want to stop DST, and there are health experts who are ambivalent. It's disingenuous to say that "health experts" want something if not all - or even the majority - actively want it.
With a field as large as "health experts" it would be a bit much to ask for a majority. Do you think that the many health experts, the fact that the American Academy of Sleep Medicine is publishing a DST position statement, and the long list of chronobiologist societies doesn't suggest there is a pretty good consensus?
You will always have a ton of ambivalent health experts on the matter because for most health experts this isn't their field.
You know you could change your working yours instead of changing "time".
Nope. Lets change time twice a year cause health problems, IT problems, car accidents.
Its already time to use a global time and stop with this bs of timezones. Timezones are an unreliable way to measure time the relation between time space.
> Its already time to use a global time and stop with this bs of timezones. Timezones are an unreliable way to measure time the relation between time space
Time zones exist because the Earth is roughly spherical. Going to global time does not change this, and so does not remove the need for time zones.
Work hours, business hours, and sleep hours in most locations will still be tied roughly to sunrise/noon/sunset.
People are still going to want uniform event times within an area--almost no one wants businesses to open 50 seconds later in Seattle than in Redmond, for example.
We will still end up with strips separated by longitude boundaries, with events synchronized within each strip. We'll probably still synchronize each strip so that events are one hour or one half hour later than the strip to their east.
To answer questions like "is it too late to call my friend in <X> now?" where X is someplace outside your strip, you need the offset of your strip from UTC and the offset of your friend's strip. From the difference of those, and the UTC time of normal bed time in your strip, you can figure out if it is probably past bedtime in your friend's strip.
These "strips" are pretty much the same as our current "time zones".
No, because people use local time to decide when to go to bed, and when to get up. Aligning that to the sun is the most important bit. Asking your smartphone what time it is somewhere else is trivially easy no matter what method you use.
I was also frustrated by the article's lack of elucidation on that matter. I think this is about as close as we come to an explanation:
>[T]here is a discrepancy between your biological clock and social clock, which researchers refer to as “social jet lag,” Dr. Roenneberg said. Permanent standard time is closer to the sun’s natural time so social jet lag is reduced, he added. “Daylight-saving time means that we virtually live in another time zone without changing the day-light cycle,” Dr. Roenneberg said. “The problem is the misalignment."
Which makes sense on its own, but it doesn't account for the variance within time zones. A Chicago resident experiences sunrise and sunset about an hour earlier than a resident of Lubbock, Texas, even though they are in the same time zone (Central). So you can't really say that Standard Time is the one-size-fits-all solution -- and indeed, the Illinois Senate just passed a bill [1] to make DST permanent in that state (although it is hamstrung by the same federal regulations that other states face after passing similar bills).
That absolutely does not make sense even on it's own. What is "the sun's natural time" supposed to mean? That seems to suggest that anyone not waking up at whatever Dr. Roenneberg considers the correct time is "misaligned." Not only does he not consider variance within times zones, he doesn't consider variance within schedules.
Depending on schedule, location, and plain personal preference, any number of time schemes could be "the best" for any given person. Ultimately it doesn't matter whose on what time as long as we are standardized to reasonable large areas, and pick something that's within a few hours of most people's ideal.
Roenneberg isn't stupid. He is saying that biological time and social time are such that setting clocks closer to solar time ends up being healthier for more people.
Also Roenneberg is quite clearly aware of the variance of daylight within time zones and the health effect that this causes. I bet he's even written papers on this effect!
Plenty of footnotes if you want to dig into the details / weeds:
> Conclusion
> In summary, the scientific literature strongly argues against the switching between DST and Standard Time and even more so against adopting DST permanently. The latter would exaggerate all the effects described above beyond the simple extension of DST from approximately 8 months/year to 12 months/year (depending on country) since body clocks are generally even later during winter than during the long photoperiods of summer (with DST) (Kantermann et al., 2007; Hadlow et al., 2014, 2018; Hashizaki et al., 2018). Perennial DST increases SJL prevalence even more, as described above.
[…]
> Summary
> Discrepancies and misalignments between social (local) clock time, sun clock time, and body clock time can be caused by political decisions: DST is one example. There are multiple health and safety consequences of these misalignments. Our goal is that this article’s facts and reasoning will be used to make clock choices that improve human lives.
Interesting and somewhat counter intuitive to me. I imagine that depends on where one lives in a particular timezone.
Personally, I prefer DST. During standard time in California, I have to shift my sleep cycle earlier relative to the clock time as I am unable to sleep once the sun is up which is typically before 7 am.
I don't want to stop Daylight Saving Time. I want it year round.
The quirk, due to the Uniform Time Act, is that States have a choice -- either never use DST or only use DST during Spring/Summer dates stipulated by Congress.
But people do travel in an ever increasing amount over timezones. Often many of them, often more than twice a year. At least here bar opening hours have been significantly deregulated over the last decades. So you can go out and drink until 4am or 5am and obviously people do that.
Compared to that the health effects of 1 hour time shift twice a year sound ridiculous to me.
The article points out that travel related jet lag is often different because it doesn't happen over and over and over however when you switch to daylight savings time you may have to be waking up an hour earlier according to your biological clock day after day after day.
In addition to the public-health issues of heart attacks and car accidents, the time-swaps are also a huge PITA for parents of young children. Kids between half a year and three years old have sleep routines that don't shift just because someone says the clocks have changed.
Fall back an hour? Congrats, your wake-up time just went from 5:30 AM to 4:30 AM because that's when your kid's still getting up. Spring forward an hour? OK, you just lost an hour from that shining window between when your kid goes to sleep and your own bedtime when you can actually get other stuff done.
Growing up in Europe, I remember the winters to be dark and miserable, but in the summer we had sun till 9:30 PM.
There are many true and false arguments PRO and AGAINST DST.
The worst I've heard is "it will upset the cows with feed times" and "it will fade more curtains".
The best argument I've heard against DST is that it would put the kids coming home from school outside a sun-hour earlier, meaning there is more UV and it is warmer. That's a valid case against, seeing it's so bloody hot here in summer.
Another case, PRO DST study concluded that the lack of DST causes people to drive home in peak hour with the sun in their eyes, causing more accidents.
At this point, I think DST is still a good thing. It's good for the economy. We don't go out to have dinner in the dark, for example. But I'm getting too old to care.
This article's arguments are very thin in my books.
> The best argument I've heard against DST is that it would put the kids coming home from school outside a sun-hour earlier, meaning there is more UV and it is warmer. That's a valid case against, seeing it's so bloody hot here in summer.
There are better arguments than that which have passed peer review:
> In Australia, in Queensland, we've been trying to get this outdated state to start using daylight savings for years.
Speak for yourself. I live in the south east and don't want DST.
> 95% of the population is in the south east.
That's not accurate - where did you get that figure? Regardless, Western Australia has an even greater percentage of its population in the southern part of the state than Queensland, and it voted against DST four times over the last 40 years.
> it's so bloody hot here in summer.
Not to mention by the time you go to bed the temperature is cooler without DST.
As long as we can all agree to stick to standard time, I will be all for any such motion.
If you want to go to permanent DST, that’s gonna have to be a hard no from me, dawg. I’d rather suffer continued switching of hours than move to permanent DST.
No, it would require an amendment to the Uniform Time Act [1]. Under current law, states can opt out of DST (subject to some conditions), but the federal executive branch can't unilaterally force them to opt out.
So then you create an executive order and then withhold federal funds from the states that don't comply. I wish states would have a backbone but with the lion's share of taxes going to DC they are just powerless.
This, if all your software clocks refused to switch times in defiance of the timezone, is there any legal problem? Make it a fait accompli and the laws follow.
Well, never mind then. Although Trump did pledge exactly this (permanent DST via executive action) during his campaign, and if anyone is going to try and ram it through regardless of legality or consequences, it's him.
That would really only work until another president and sympathetic congress issued a counter decree. Granted, I’m sure by then there would be significant pressure to not undo it. That doesn’t always stop them though.
The second topic, the main one that circadian scientists talk about, is chronic risks, and I believe they are more important to our health. To follow this logic, you have to believe that people will continue doing whatever it is they do today (e.g., going to bed at midnight), and won't shift their schedule around right away to optimize sleep--i.e. they will not recognize that their body clock is set mainly by sunlight. The campaign to change school start times has been going for 25+ years already, so fast changes here are pretty rare.
When the clocks change, people wake up at a different circadian time, and if that time is too early, it is associated with worse health outcomes.
Some large-scale epidemiological tools have been used to figure these things out. One compares the difference between sleep patterns on "work" days and "free" days - like how much do you sleep in on a weekend? (Till Roenneberg's "social jetlag"). A second method uses "position in timezone" - comparing people living on the eastern or western edge of a timezone in various ways.
Roenneberg's work from the mid-2000s showed that night owls suffer a lot under "wake up before the sun" kinds of schedules (their "social jetlag" is bigger) - it makes them fatter, more irritable, get more diabetes, etc. They don't go to bed any earlier, but they're forced to wake up earlier.
Next, when you look at timezone position (this has been done for millions of people), people on the western edge of a timezone (where the sun comes up later but the clock is set at the same time) are quite a bit worse off for cancer rates and obesity - 10-20% more for some kinds of cancers, and a roughly 20% increase in chances of being obese.
I'm worried about these chronic health problems, so I've been writing and advocating for standard time: https://medium.com/@herf/why-standard-time-is-better-e586b50...