Sometimes people disappear after they'd been here a while, there's no rhyme or reason for it that I've ever been able to find- and that includes those who were here when I was new. Sometimes the people who disappear come back, but they don't remember this place. My own brother has been here, disappeared, and returned three times now.
Sometimes there's more than just fog outside the doors- other places, other times, worlds you could never imagine. Sometimes they're horrible, like whatever this week has brought on us. Sometimes they're harmless. There's no reason for it, either. But if you're not back inside the hotel by the next time the clock chimes, you get left behind. The only way we've ever been able to figure out home is waiting here until you get sent back.
If one of those things roaming the hotel manages to kill you, you'll come back after the cycle is up. Just don't die outside the hotel.