Also, might be his lack of control due to inebriation, not that that is a defense... because people who get that way shouldn't drink in excess, whatsoever. Or he could be touching you while he's asleep, as a subconscious thing, which is less his fault.
Either way you just need to avoid being near to him, and see if he makes an effort to do this to you. And maybe next time he's doing it, touch him back (with a swift slap to the hand) before alerting the others in the room.
This is going to come to a head somehow, and you should have some kind of backing when it does if you can, seeing him out of position might make your other friends see the light, as it were.