After a full day at college, I would return home and go straight upstairs to my room; specifically to my computer, only going down for dinner.
Hmm, that's what my days at college and school would consist of mostly. I didn't have any interest in socialising with anyone outside of computer games. I was into World of Warcraft at the time.
The only other cause of a different kind of shutdown is in a supermarket like Tesco's or ASDA, as the longer I spend in those kind of environments, the more absent-minded and distracted I am.
I think that's most of a sensory overload if you're getting distracted by a lot of things.