See that is the thing, he has already gone thru all that he is 4 years old. He won't chew on anything else that is not his. I have a pair of shoes that I always leave by the door and he has never touched them. When I first got him he shredded magazine left on "his" couch, but nothing else. I think its bad for them, that wood can not be easy to digest!!!!!
My guess is he's mad he can't take a shower with you.
My guess is also, the excercise. Attention and exercise are two different things. He needs to burn some energy. :) When they are bored, they will become destructive. Not sure, why he is just picking on the wood night stand.
When you can't supervise him, can you crate him, even though he is older, it may help. The more they get in a habit, the harder to break.
Get some bitter spray from the pet store. I forget the name of the stuff I used. It was an all natural product. The dog wont like the tast of the stuff, be careful not to touch your own mouth before you wash it..nasty.
Also, there are many toys out that you can add a treat inside that will keep them occupied until they get it out. We went a cheap way (if you call it cheap) by taking the balls that came on the rope after the dog chewed the rope off and fill it with a bacon treat and a milk bone to hold it inside.