Tony writes:

One human factor that's been overlooked -- on late night flights, it is
often very very quiet aloft. I like the sound of a human voice from
time to time, it's reassuring to know the coms are working. Listening
in on aircraft to aircraft frequencies, and chatting as well, is I
think a safety factor. Pilots who make long cross country flights will
understand the reality of my point , others may appreciate at least the
theory.

I think the ATC guys get just as lonely - I think I've had them start up the
conversations late at night more often than the other way around.

One sticks in my mind for some reason even though it was quite a few years
ago. The Wilkes-Barre, PA controller said something like "Hey, aren't you
guys the ones who make the sausages?" I was mistaken for another aircraft
with a similar call sign that flew the same route frequently late at night.
We had a nice chat for the few minutes that I was in his airspace.

BDS