Maybe he's staring at the ceiling. We haven't heard anything about his glasses, so I assume he has those at night. In January, they took them away for a few nights (but left him with his underwear... strange).
He could be sleeping, but it's got to be cold. No clothing whatsoever. A single, abrasive blanket. The only pillow, built into the mattress. It's probably not consistently quiet or dark, either, and he's unable to curl up against the wall or cover his head.
I can't sleep without a pillow between my legs and the ability to adjust my head pillow when it gets too warm. I'd be fine with the naked part, but if I get cold at night, my body can't warm up without another blanket. So I'd be staring at the ceiling. Which is awful, knowing that when I am prodded alive again at 5 am, I won't be allowed to sleep for another 15 hours.
There's no way he hasn't run our of random shit to think about at this point. During the day, he gets a book and a magazine. Hardly enough to occupy a whole day of brain activity, but it's something. At night, no such luck. I wouldn't be surprised if the shred-proof blanket were the only object he can interact with in his cell from 8-5 every night. For 223 nights, that's been it, give or take some underwear.
At some point, I imagine you just shut your brain down so there isn't so much noise to deal with - too many thoughts you can't do anything with. Not now, not in the morning.
Does he even have a clock in there? Lost all night long, never knowing how much longer til it's time to stand nude, at attention outside the cell door once again. It must be terrible, spending the whole night anticipating that, never knowing how much longer before another day full of humiliation begins.
This is wrong.
h/t to sweeper for the idea.