Plenty of instances in fiction where the hero whether a diviner or not was wakened by strange dreams. You could also rule that the diviner has strange alarming dreams that give him a bonus to wake up as he hears noises from the ensuing combat. You could also rule that his divinations are most powerful when his own well-being is threatened so if one of the wolves is about to rip his throat out in his sleep ... BAM he wakes up and is looking frantically around for the cause of his anguish. If a wolf is threatening close kin, a wife, girl-friend, or a friend closer than a brother, you could wake him in that situation also. However you're the gm, your game your call. I would add this caveat, the players are supposed to be the heroes and your game is supposed to be about them. Hopefully, you're not trying to recreate that awful Liam Neeson movie that pitted him against some wolves.