You don't have to relog.
Everquest has a system that automatically turns on non-patch required features. It is directly in sync with their PC server clock.
Fabled and 10th Anniversary events are/were a good example of this in action. I stood staring at some Lizard men in Cazic Thule and right before my eyes at 12:00 midnight PST, they depopped and repopped instantly as tougher mobs.
There are some Dev posts about this mechanism if your Google Fu is strong.
____________________________
After 16 years, I'm not listing every friggin character.