Often in skyrim when you enter a city at say 2am, instead of being in their homes/sleeping NPC's will be walking about the streets or just starting to head home from places instead of already being there.

It's annoying and immersion breaking, especially when playing as a thief character. I have mods that add extra npc's to the game so its more obvious, but it happens with vanilla npcs too.

Is there a mod that fixes this? I've read it can be linked to turning off vsync, but no idea if theres any truth to that.

Is this a vanilla glitch? Can't recall ever having this issue.

EDIT: On the other hand, I've been using the Unofficial Skyrim Patch since forever and I notice that you get 39 hits when checking its changelog for "schedules". So adding the unofficial patch would be my initial tip if you aren't using it already.