Being an astronaut seems cognitively expensive. Your time is regimented down to the minute. Your space is regimented down to the inch. The things you bring up and down, including yourself, is measured to the pound. I would imagine you have to constantly be evaluating, assessing, and thinking critically about everything you do all the time. And then to suddenly not have to do that and just live in the moment has to be a massive readjustment.
Your comment lead me down a rabbit hole of space micromanagement. OSTPV (onboard short-term planner viewer) is the software they use to basically schedule every minute of your space flight. Basically every day someone from earth decides what you do, when you eat, when you exercise and will make changes in realtime.
Great read here with a video of someone using the actual software: https://blogs.esa.int/iriss/2015/09/09/playing-with-playbook...
There's a popular clip from Joe Rogan out there where he says "Be the hero of your own movie. If your life was a movie and it started now. ... What would the hero of your life’s movie do right now? Do that. Do those things."
So it's interesting that this cognitive state is helpful for some people to visit in a transient or metaphorical way but becomes weird when it's persistent. But it does seem potentially related in that maybe it originates from a kind of conscientiousness in the astronaut profession