Reading the Shema

This can perhaps be understood by examining the issue of the beginning of the blessings. There we see various indications for the time of the Arabic prayer, and it seems that the time of the evening prayer is a sign and not a reason. If so, then even if the actual time of the evening prayer changes today, the halakha remains the same.

I remember that it can be shown from the issues at the beginning of the blessings that this does not depend on the time of lying down and getting up, which change with time and culture.
I have already forgotten the evidence, but some of the discussions there that clarify the time of reciting Shema according to the definition of day and night also point to this.
And there is also a puzzle about all the lessons, such as from the time when the priests enter to eat their offering, from the time when the poor eat pato, from the time when people enter to eat fatom, etc. etc. If people enter to eat fatom at that time, it turns out that it is not time to lie down but time for a meal. Rather, it should probably be said that this is the appropriate time for lying down since it is already dark enough, although in the accepted culture people usually do not lie down to sleep yet, but rather dine.
And so at dawn, since there is already light and one can function (recognizing one's friend from a distance of four cubits), it is time to be awake, even if people are still sleeping. And for the sons of kings, as long as the time is closer to sunrise than it is closer to noon, it is the beginning of the day and is considered the time to get up (but if the sons of kings start getting up after 3 hours, when noon is closer than the beginning of the day, this will probably have no effect on the halakha).

Ronnie, that's exactly what I wrote above.

Yes indeed. I just expanded a bit.

In the book of answers by Rabbi Yosef Chaim Sonnenfeld. Keren Ram Institute, Jerusalem, 5621;5, end of paragraph 23:

And I will not refrain from raising this issue, especially since the Torah has suspended the issue of K„sh in lying down and getting up, and it is not written in the Hadith of Time, if the way of people from the weakness that has descended to the world changes, and now everyone sleeps longer or gets up later, there is a place to say that there is an obligation from the Torah here, and although I did not find this explicitly, for the sake of the reader the explanation is correct, and even more so where the nature of the climate causes this, all the more one can say, may they rest in peace with Israel.