I don't think this is a cultural thing and I haven't been able to find a basis for it or even anything remotely similar from a cultural/religious background. I think they might just be a bunch of weirdos.
Madness string 96984
Between the hours of 1am-5am, the world is quiet and no one expects anything from me. I could stare at my wall for 4 hours and there would be no consequences. It's so silent and calm. I love it.