The folks who study this:
* https://en.wikipedia.org/wiki/Chronobiology
Seem to have come to a consensus that if we're going to get rid of DST, then health-wise it is best to have Standard Time year-round:
> As an international organization of scientists dedicated to studying circadian and other biological rhythms, the Society for Research on Biological Rhythms (SRBR) engaged experts in the field to write a Position Paper on the consequences of choosing to live on DST or Standard Time (ST). The authors take the position that, based on comparisons of large populations living in DST or ST or on western versus eastern edges of time zones, the advantages of permanent ST outweigh switching to DST annually or permanently.
* https://journals.sagepub.com/doi/full/10.1177/07487304198541...
For a longer-read, referencing quite a bit of academic literature, but a conclusionary snippet:
> 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.
* https://www.frontiersin.org/articles/10.3389/fphys.2019.0094...
Other position papers that I've dug up over the years when curiosity got the better of me:
> Society for Research on Biological Rhythms (SRBR) is dedicated to advancing rigorous, peer-reviewed science and evidence-based policies related to sleep and circadian biology.
* https://srbr.org/advocacy/daylight-saving-time-presskit/
* (refs, with pro and con): https://srbr.org/wp-content/uploads/2020/09/DST-References-S...
European Sleep Research Society:
* https://esrs.eu/wp-content/uploads/2019/03/To_the_EU_Commiss...
American Academy of Sleep Medicine (with 36 footnotes if you want to dig further):
* https://jcsm.aasm.org/doi/10.5664/jcsm.8780
* https://doi.org/10.5664/jcsm.8780
The Centre for Chronobiology, based at the Psychiatric University Hospital (University of Basel):
* http://www.chronobiology.ch/wp-content/uploads/2019/08/JBR-D...
If people stay on DST and it turns out that starting the day an hour later is more beneficial, then life will simply gradually adjust.
> For example, New York’s social clock closely matches the sun clock in winter during Standard Time: when the social clock says it is noon, it is very close to midday, the sun’s highest point in the sky. During DST, however, New York’s social clock shows noon when it is only 1100 h by the sun clock. People who have to get up at 0600 h by the sun clock in winter have to get up at 0500 h by the sun clock under DST, despite the social clock showing 0600 h. Essentially, they have to go to work in 1 time zone further to the east. This means that people in Chicago have to work during the office hours of New York, and people in Berlin have the office hours of St. Petersburg. Instead of seeing DST as working according to one time zone to the east, one can also think of it as people’s body clocks being pushed further west within their time zone (or social clock). Since the body clock follows the sun clock, these changes can affect our health.
* https://journals.sagepub.com/doi/full/10.1177/07487304198541...
> An understanding of time zones is essential for appreciating the effects of DST because switching to DST is nothing else but assigning the respective location to one time zone further east. This switch increases the discrepancy between the sun clock and the social clock by 1 h. This means that for Galicia [Spain] during summer, it is only 9:30 am by the sun clock when social clock claims noon, since they now have to live according to the hour-meridian that runs roughly through St. Petersburg [Russia].
* https://www.frontiersin.org/articles/10.3389/fphys.2019.0094...
All these arguments against a timezone change, removing the shifting to/from DST, etc are predicated on the assumption that the times that schools, work places, restaurants, public amenities, etc open and close through the year are not allowed to change.
This seems to be a surreptitious strawman argument against TZ/DST changes, as there's no legal or regulatory reasons to prevent any of these institutions changing their hours of operation.
* https://www.frontiersin.org/articles/10.3389/fphys.2019.0094...
> For example, New York’s social clock closely matches the sun clock in winter during Standard Time: when the social clock says it is noon, it is very close to midday, the sun’s highest point in the sky. During DST, however, New York’s social clock shows noon when it is only 1100 h by the sun clock. People who have to get up at 0600 h by the sun clock in winter have to get up at 0500 h by the sun clock under DST, despite the social clock showing 0600 h. Essentially, they have to go to work in 1 time zone further to the east. This means that people in Chicago have to work during the office hours of New York, and people in Berlin have the office hours of St. Petersburg. Instead of seeing DST as working according to one time zone to the east, one can also think of it as people’s body clocks being pushed further west within their time zone (or social clock). Since the body clock follows the sun clock, these changes can affect our health.
* https://journals.sagepub.com/doi/full/10.1177/07487304198541...
> Although DST has always been a political issue, we need to discuss the biology associated with these decisions because the circadian clock plays a crucial role in how the outcome of these discussions potentially impacts our health and performance. Here, we give the necessary background to understand how the circadian clock, the social clock, the sun clock, time zones, and DST interact.
* https://www.frontiersin.org/articles/10.3389/fphys.2019.0094...
I've read about chronobiology. It's well established light exposure just before and after sleep are the primary zeitgebers. I think it's fair you support your claim instead of expecting everyone else to read several thousand words looking for something probably not there.
Still, maybe if that's the only way to kill switching clocks twice a year, it might be worth it and we could end up with later hours like Spain.