At what time does the DPPT switch between the day theme and the night theme?

Question

Alternate rewording: When does the game count day and night according to the internal clock?

Comments

Per https://pokemondb.net/pokebase/meta/82128 we're not closing specific questions because a broad question exists.

Answer 1

Night music will begin at 8:00 pm and go until 3:59 am.

1. Morning: 4:00 am - 9:59 am
2. Day: 10:00 am - 7:59 pm
3. Night: 8:00 pm - 3:59 am

Time in Generation IV (Bulbapedia)