He blames his sinuses, but this has been going on for over a year. He keeps a box of Kleenexes by his bed for this reason. Is this normal?
I'm not a doctor, but I'd venture to guess it has to do with vasodilation, or enlargement of the blood vessels, in his eyes and nose. (This is the same reaction that causes the "flush" of red skin coloring during sex.) A few people have a similar reaction and sneeze when they orgasm. I'd say its normal. But as always, he should check with a doctor if anything seriously concerns him.