While I agree that there is an outside possiblity that the vividness of the dream could have produced bite marks on his hand, I merely think that is is highly unlikely.

The problem with "phenomena" is that they are too often reported in only eye-witness accounts of a single person or two who happened to experience something abnormal. Whether or not there were supernatural causes for whatever they experienced, the world around them can only meet them with skepticism for they have no evidence of any kind to back up their claims. We do not know the extent to which the world around us can be influenced by extraordinary means, but we do know what is regularly observable. People become injured all the time in their dreams but wake up with nothing but a memory, if that, of the experience they encountered. Bookshelves collapse frequently because of a shoddy base, a shift in a building's foundation, or a displacent of weight which can cause pressure to slowly build up over time and then release. But what about the times when there are strange bumps in the night, scratches that appear in flesh in the morning, or things that are just plain weird during the day? Often the observer has just as much reason to believe that the cause was something supernatural rather than logical, because there is no evidence one way or the other. However, there has yet to be an experiment proving such things as being supernatural. Not that they aren't, but at this point it's just speculation.