I think psychosis as of now is just a terrible mechanic. It’s very easy to spot and is flat out no threat to you or anyone around you.
Here are my suggestions.
Remove the dead giveaways of psychosis. The invisible shadows goes to the top of this list.
The debuff on your character as well you should not know if you are going insane unless you are somewhat clever or have teammates diagnosing you. Or can self diagnose with a medical scanner.
My next point would be is adding a “fake” damage mechanic. So things like fake fires are an interesting mechanic till you walk through it and take no damage. But what if you did? The whole “body can’t live without the mind” is you going so insane that you start to think you are dying.
You think the fire is real because you think it is actually killing you. So you start to scream there is a fire and begin using the fire extinguisher on it. Which your teammates see. If your character’s fake health reaches 0 your character will become comatose.
Finally I would suggest adding things like characters, your crewmates transforming into creatures when you experience psychosis.
The kicker would be having the creatures “attack” you if they get in close proximity to you.
Imagine you go outside and get blasted by a watcher so you run back to the ship thinking “shit that was close” you board the ship and your medic runs to treat your psychosis but all you see is a mudraptor charging at you. So you shoot it.
To sum it up.
Make psychosis difficult to spot
Make it a threat
Make it a threat to the sane people around you.