Do I let a sleeping dad sleep?

My dad is 78, has slight dementia, was diagnosed with cancer, and now lives in a LTC facility. It’s been one hell of a year but he’s been a trooper and for the most part, has been pretty content. I usually visit dad every day (and stay anywhere from 2 hrs to 4 hrs). People have told me not to visit so often, but I feel like I have to - for dad. Usually our time together is positive and it makes both of us feel happy. Lately dad has been exhausted. The doctors thinks his sleeping at night is being interrupted (and she’s looking into whether or not there’s something else going on) but my question is DO I STAY OR DO I GO? For the past few visits, dad is falling asleep. He’s obviously tired and I think the sleeping is good, but this time of year is crazy and I could certainly use the extra time to get things done at home. My dad is not the type who would ever want me to stay if I’ve got other things to do but I don’t want him to think that I’m leaving BECAUSE he’s not talking. He can’t help that he’s tired because there really may be something else going on. How do I communicate in a positive way that if he needs to sleep - I leave? Sometimes I worry that something else IS going on and I don’t want him to feel deserted. Ugh