Do you have any sources for those claims by "health experts"?

Timezones and DST were largely instituted in the era of 7-15h work hours (still remaining in plenty of govt institutions), and we are more in the 9-17h realm today, so society has already "timezone-switched" in the last ~100 years (quite a bit simplified, ofc).

I'd be surprised at how come one gets sleep deprived from having a pre-set timezone that doesn't jump around ever for a location? If you go to sleep at 9pm (way past dark time in the worst morning-case) and the sun only comes out at 8am, you'd be sleep deprived if you wake up at 7am (10h of sleep) because it's dark outside?

See a nibling post for sources: https://news.ycombinator.com/item?id=30691158

As for the 09:00-17:00 era. That is largely untrue in most of America. School still starts at 08:00 in most places, industrial and production workers often start at 07:00 and work until 16:00. The largest employer in my town is a production facility and operates between 06:00-15:00 or even 05:30 and 14:30. It is only true of white collar jobs like ours that the 09:00-17:00 is the dominant hours.

> School still starts at 08:00 in most places

School starts at 08:00 because work starts at 09:00 and parents want to drop the kids at school on the way to work.

> The largest employer in my town is a production facility and operates between 06:00-15:00 or even 05:30 and 14:30. It is only true of white collar jobs like ours that the 09:00-17:00 is the dominant hours.

As far as I know where jobs have regulated opening hours (e.g. government agencies, banks) those hours are generally 09:00-17:00. A facility that's already operating e.g. 05:30-14:30 is much more likely to be able to adjust its hours.

I don’t think it is that simple for an industrial or production facility to simply change their operating hours. They are often dependent on supplying logistics, worker availability, commuting options etc. A production facility in SODO might operate between 06:00 and 15:00 because they need to get their production onto a freight that leaves at 16:30. An industry might start at 07:00 because they work with perishable product that arrives with a lorry at 06:30 and it is really important that the lorry doesn’t get stuck in rush hour traffic.

The workers might see this as a benefit because they most often commute by car and they get to beat rush hour. And then you have a worker culture which is really hard to change.

> A production facility in SODO might operate between 06:00 and 15:00 because they need to get their production onto a freight that leaves at 16:30. An industry might start at 07:00 because they work with perishable product that arrives with a lorry at 06:30 and it is really important that the lorry doesn’t get stuck in rush hour traffic.

> The workers might see this as a benefit because they most often commute by car and they get to beat rush hour. And then you have a worker culture which is really hard to change.

Well in that case it doesn't make any difference to them whether we're talking about changing clocks so 09:00 is 1 hour earlier, or other companies changing their starting time to 08:00. So I don't see how this is an argument for one or the other. If your position is that other companies shouldn't be allowed to change their start time (one way or another) because it might affect this production company, surely that's the tail wagging the dog.

Thanks: those are quite interesting.

I wonder where the preference for DST then comes from? I've replied to that thread with a question of what the population distribution is in regards to West/East sides of timezones, and I also wonder does this apply if we move the timezones even further (another 1h or 2h?). Basically, it would indicate that the modern rhythm is out of whack, though it'd be harder to test that.

> I wonder where the preference for DST then comes from?

For me, I simply want more daylight in the evening.

I don't give a shit about waking up with the sun. I'm going to sleep until 10 or 11 AM on the weekends anyways, so I want the daylight to be shifted later so I have more daylight to do things.

Somewhere else in this thread, someone put forth the idea of a fixed dawn at 7 AM. I'd rather have a fixed dusk at 9 PM. That would mean that the sun might not rise until after noon during the shortest days of the year, but that's fine by me. Obviously, such a system is not feasible (We'd have to change our clocks every day!), but if it was, it'd be my preference.

The way I heard the story—and that story is almost certainly fictional—preference from DST comes from legislators—at a time when they were all upper-middle to upper class white men—that only knew cushy 9-17 jobs and valued their own ability to go home and have a barbecue over everybody else’s ability to wake up with the sun. I bet HN’s demographic aligns pretty overwhelmingly with the preference for an after work barbecue.

But that's not in line with those studies: I'd expect people in Eastern sides of timezones to prefer DST, which certainly includes cities like Boston or New York or Washington D.C. And vice versa, those in Western parts to prefer standard time.

Still, even if we allow for 9-17 employees having these preferences, they'd be waking up in the dark hour (somebody mentioned Sun rising at 8:30 in SF in late December with DST, and 7:30 without, which still precludes most of non-white-collar jobs too, and depending on the commute, some white collar jobs too).

Not questioning you, ofc, just wondering why none of the stuff adds up? :)

As for HN demographics, I am not sure that's true: while they are mostly white collar workers, they also get a lot of flexibility so they could probably just get up a few hours earlier to start working for more afternoon daylight.