Sleeping most of the time?

You don’t give a lot of information. Your profile is empty.

How old is he? You mentioned socializing. Does he see anyone other than you? Does he participate in anything?

Older people get very tired.

Sleeping a lot could be "normal" or it could be a sign of depression.
If he is able to participate in Adult Day Care or a few hours at the local Senior Center that might be good for him. as well as for you.
Socialization is also important and could be a benefit in that it will give him something to do and help keep him engaged.
Sleeping a lot is common if you think about it even a quiet day at home can be exhausting for a brain that has to sort out all the various things that have been going on. Even something as simple as eating a bowl of cereal has a lot of steps that have to be recalled. Pick up spoon, get food on spoon, lift it to the mouth, put food in the mouth then chew and swallow, repeat again and again.

This is normal for the end of life.

you should have him evaluated by hospice.

both of my parents began sleeping a lot (18+ hours a day) in those final few months. My Mom wasn’t awake long enough to actually get nutrition during the final 2 months.

this is normal. The body is tired and worn out,

I wish my Mom had slept. When she was in her own home, she always napped in the afternoon. At my house, rarely and up at least once at night.

If this is the end stage, then I think they sleep alot. Not really sure how u can keep someone awake.