Or you could simply read the article. Ctrl-F "circ" is handy:
> 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.
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.
> 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...