Label EVERYTHING in his room with post-it notes. like 'lamp', 'lampshade', 'lightbulb' 'lamp switch' etc. go into as much detail and use as many as you can. If you're thorough, he'll be finding them for months/years and it'll make him smile every time he discovers one.
We did this to a newlyweds' house when they were on honeymoon; It's super effective and entirely harmless. Win.
I like this one the best. It seems like the one that would make me the least angry.