Sidewalk Stare (Score 1)

I live in New York, and we have a term for the end effect of all this strain. We call it 'sidewalk stare'. I've walked not two feet from someone I know on the sidewalk, and had to reach out and touch their arm to get them to notice me. It's not that they were staring at the concrete, their eyes simply pass over your face and they don't recognize you.

Think about it this way; Understanding expression consumes an enormous amount of processing power. Taking a sub-second glance at a person's face and intuiting their mood, which you do without trying, chews up calories and other cerebral resources. If you stand on the corner of 18th and 6th Ave. around lunchtime for a minute, you're likely to see literally hundreds of human expressions. You can't stop your mind from distilling all those mental states, because human animals' minds are built to do exactly that. It's exhausting, though you don't always notice it.

Moving around in a crowded city is mentally and emotionally taxing. Some people thrive on that, and some people are seriously impaired by it. I don't know of a selection criterion other than moving to the city and seeing if you like it, but I think if nothing else it's easier when you're younger. When people talk about being 'tired of the city', I think it's a side-effect of the aging process. All that background effort is, overall, more taxing than it was.

An interesting corollary: The more money you have, the less of this you have to deal with. Hired cars, large apartments, spacious offices, and frequent vacations all keep this from having as much of an effect.