A large part of why we're here is to be subjects in a number of human factors experiments. The experiments are designed both to find out how humans adapt to isolation, crowding and other conditions relevant to long-term space exploration, and to explore remedies for known problems. So, we're measuring, tracking, introspecting, and filling in questionnaires all the time. It's a pain, but worth it (we hope).
Last night, I started my turn as a subject in the CASPER sleep study, which involves sticking electrodes on your chest, plugging them into the LifeShirt you're wearing, plugging the LifeShirt into a PDA, filling out a questionnaire, then having a relaxing night's sleep. Here's me getting wired before bed:
The gear was actually quite comfortable, but the idea that someone is going to be analyzing your vital signs to determine how good you are at losing consciousness can induce a bit of, well, performance anxiety. I didn't lose any sleep over it.