Sleeping on Trains!

I've seen a lot of articles which mention the 'National Obsessions' of Japan, or 'National Pastimes'--odd little things about the Japanese, like swiping each others towels at the onsens, or, one of the first questions I'm always asked is, "Nan-sai desu ka"--"How old are you?". To me, though, this is one of the oddest (it's very common--I took all of these this weekend):

Sleeping on trains!