There could be a number of reasons why your coonhound howls at night. It could be that they are bored and lonely, or they could be trying to communicate with other dogs in the area. It could also be that they are picking up on sounds that we can't hear, or they could be experiencing some sort of medical issue. If your dog is howling excessively, it's best to consult with a vet or behaviorist to rule out any potential problems.