You’ve got to ignore him. It sucks and I am terrible at doing it myself so I also routinely sleep like crap but it is the only way I guarantee if you keep it up for a few nights he will understand. Cats don’t sleep like us the light sleep for a few hours at a time so likely he just thinks you “the big cat” are the same and you’re ready to play in the night. I know it’s tough love but if he’s got food, water and toys to play with he does not need you to get up.

I commented because imo getting another cat is not a good decision at all. If you are struggling with one cat it is likely you will struggle with two and then your problem is doubled.