I've often said, particularly back when it was in vogue for others to laud their boredom on craigslist to entice sex, that you could lock me away in a white walled room with no windows and I'd remain thoroughly entertained.
I adore thinking. It's probably one of the better reasons to not be dead. One of the truly wonderful dream states to enter is an area of mind whereby all dreaming ceases, all external contact with the sensory world disconnects, such that all you have are your thoughts existing in otherwise nothingness. It must sound to the uninitiated physical ear torturously lonely yet experiencing the self by itself is not scary at all. Being solo has a way of making sense to the soul.
But living is about interacting. And the brain's plasticity might in part depend upon our attentions outside of ourselves. Certainly we create new neurological paths through our own thoughts but even when we think, even brilliance can be for that particular person mundane, rote, and so, by itself, not as conducive to plasticity as might a new day on an assembly line or arguing before the court. Changing a job, from assembly line to janitor might do more for plasticity than changing venue or taking on a new case argued with time worn though still effective enough to get the job done skills.
So the point is well taken that people need to become more comfortable with their thinking, with thinking at all. But also what animated life does not require sleep? The mind tends to race and sometimes if you can't get away from your thoughts they will overtake.
I, however, prefer meditation to electroshock therapy.