At the very least there must be some kind of very broad bell curve or something, with extreme outliers on both sides. There are people who spend years in a cav

At the very least there must be some kind of very broad bell curve or something, with extreme outliers on both sides. There are people who spend years in a cave or closed room practicing meditation. If done properly, there don't seem to be any negative side-effects. I'm sure the fact that it's a voluntary activity is very important - as opposed to involuntary confinement to the solitary cell.