It depends on your condition. I "luckily" (in this case only, pretty much) have narcolepsy so when I went in for my multiple, way way too many, sleep studies I never had an issue falling asleep. The only issue is waking up and needing to piss. There's an actual human sort of watching the people all sleeping and they'll chime in immediately when you wake up (like some scifi shit) because they have your heartrate and brain scans going plus monitoring your facial movements, body movements and a camera to just see you overall. So they'll come over the intercom in your room before you move around too much to be like "are you ok?" And you just talk out loud to this disembodied voice and a nurse or technician of some sort will come in and disconnect the main wires so you can go piss... it's a surreal experience overall. I don't know how more normal people do manage to sleep. Like for me it's not an issue, but if someone suffers from less symptomatic stuff I can see them just laying there like "why do I have this plastic tube stuffed up my nose and goo leaking down from my hair...?"