We tend to forget that dogs do not communicate in the same way as humans. For example, humans make eye contact when communicating and make contact through an open hand shake. Both of these behaviours may be seen as a threat to dogs.
Training is the key to preventing dog bites.
Dogs, children and adults need to be trained in how to approach and communicate effectively. When awoken from a deep sleep, humans have been known to behave defensively, that is to strike out. Dogs when woken in fright may behave in much the same way. Dogs should not be disturbed when sleeping. If you need to wake the dog up, call them from a distance to allow them time to become oriented.