[tenderfoot]

Unless there is a medical problem, a 4-yr old dog should not be making mistakes in the night. But since he has shown he can't be trusted right now then you need to treat him like an un-housebroken puppy again, until he can prove himself.
Take his water away at about 7 pm and give him lots of chances to pee just before you go to bed. I would either tether him to my wrist on a 2-3 foot leash (if he is sleeping in bed with you) or on the same short leash to the bed. Just long enough for him to stand up, turn around and lay down again - but not so long that he can go pee somewhere and then return to a dry, warm bed. Crating him (in the bedroom) would be another alternative to the tether.
If he wakes up and seems frantic to potty then you can take him out (make it very business like - its no time for play or loving), but if he just seems a little uncomfortable, try to tell him to lay down and go to sleep again. It might be that this has just become a new habit in the night and he needs to be told that he is to sleep through the night and not get up.
Then get up in a timely manner in the morning and let him out to releive himself.
Some good exercise before bed should help aswell - he will sleep more deeply if he is tired.