Although I mainly know of National Post for its hosting climate change fake skepticism, this article about the psychological problems that have been found on long space missions is quite good. For example:
In space flight studies, the worst manifestation of this is known as
“third-quarter syndrome,” for its typically late onset in a mission. It
was shown for example, in the Mars500 crew who emerged in November 2011
after 17 months in an isolation pod in Moscow, with ailments that
included severe insomnia.
“I’ve lived it, and I can describe it,” said Pascal Lee, a planetary
scientist and co-founder and chairman of the Mars Institute, who has
done 30 expeditions to polar regions, including as director of the
Haughton-Mars Project in the Canadian High Arctic. Priorities shift once
you get past the climax of a mission. “You get tired of holding back.
You get tired of accommodating other people’s quirks and idiosyncrasies.
… It’s psychological erosion.”
Missions to the International Space Station have typically lasted six
months or so, and psychological research has shown, over time, negative
feelings get displaced onto mission control, breeding resentment.
People get irritable; they make more mistakes. They get cabin fever on a
cosmic scale. One study documented “psychological closing” among
astronauts, who picked favourites among mission controllers and
perceived others as opponents.