Think that king might have a rather disrupted sleep schedule? It seems obviously insane to live like that, no? Instant reaction is "my god, why would you do that", right?
Consider that a totally ordinary middle class house in the West is arguably worse than that.
No wonder everyone "can't" sleep or "is just a night owl" (sure, some may actually be, not saying zero people are).
Frankly it's a miracle we get anydamnthing done, and sleep at all.
I'd encourage everyone to try candle-only lighting after sundown (or maybe extremely dim candle-temp electric lighting, though if you're just trying it briefly consider the candles, they're a bad idea for a bunch of reasons long-term but fine for a few days—you'd be surprised how little you need, I found two beeswax tapers were the minimum to read by without discomfort, but my eyes are still young-ish), no electric devices whatsoever (there's actually still a ton you can do—card games, board games, play music, read, draw, write, et c.), no whole-room lighting, just for a week or so. See if you're still a "night person" by day 7.
[EDIT] Bonus round on the thought experiment at the top: imagine the king is, despite this questionable decision, actually fairly responsible and leaves the castle to go run the kingdom during the day, most days, retiring to this ultra-carnival-home only late in the day. You'll expect that to go even worse as far as sleep is concerned, right?