![](https://ffxiv-roleplayers.com/mybb18/images/reksio/flecha.png)
I'm afraid such a fast rotation of Hydaelyn doesn't make sense on a physical scale. Such a high speed would have drastic changes on the winds, for example. I'll poke a friend of mine who's an astrophysicist so he can do the math for me (I'm lazy and bad at maths).
But besides that, there's nothing in lore determining that Eorzeans stay awake for various cycles of daylight before going to bed. Since the simplest solution is the most probable, it's more likely that this is just a gameplay representation for aesthetics (so that people that log in at night aren't doomed to have only a night-time game world) and for certain mechanics (I think weather and daytime affect fishing in some way).
But besides that, there's nothing in lore determining that Eorzeans stay awake for various cycles of daylight before going to bed. Since the simplest solution is the most probable, it's more likely that this is just a gameplay representation for aesthetics (so that people that log in at night aren't doomed to have only a night-time game world) and for certain mechanics (I think weather and daytime affect fishing in some way).