VOY indicates that crew health and brain waves are monitored at all times.
That's super creepy.. Eeeeeeww
Yeah, but, like, Tuvok can barely go three weeks without catching a case of temporary insanity. You have to take some reasonable precautions.
Yeah. Given the potential for brain parasites, alien possession, mind altering drugs, etc. brain wave monitoring might be a small price to pay to protect the crew.