Go to the pet store and buy "apple bitters" it gives off a bad tasting harmless scent and dogs dont want to chew it, i used this on my couch, just dont put it on the arm rests or anywhere you might touch often because once it is on your hands and you touch your mouth or food it will taste awful, so wash your hands after spraying the dog bed.
Go to a pet store and get him a hoof to chew. (yeah, a hoof) It lasts a long time and won't fill his stomach like rawhide. Play, for at least 15 min-1//2 hr before bed. Make sure he has a few toys, (ball and rope bone, squeaky depending on type of dog) food and water. As inconvenient as it is, spend a few nights checking in on your dog. when does he tear up his bedding? Some dogs like to "bury" things in their bed. If it's a big dog, use an old comforter folded in fourths. "Digging" in it will mess it up, but not tear it up.