The cause isn't known, but it probably had something to do with that head injury mentioned in the article. I've heard before that a bump on the head and cause a concussion and that going to sleep with such might mean never waking up.
![Sad :(](http://cdn.vgws.com/common/images/smilies//icon_sad.gif)
He was a great salesman, always being energetic and enthusiastic about the products he was promoting. He really made them seem like great things to have.
For an eerie coincidence, the last time I saw Mays on TV was an appearance on the Tonight Show. I believe that was the same day Ed McMahon died and the show had a tribute to him.