Why is my dog barking at night?

If your dog is separate from your bedroom, separation anxiety may be the cause (which moving him closer to you would likely resolve). If your dog isn't getting enough exercise to tire him out, he may stay awake barking at shadows (the solution is to take him on longer walks or runs so he is tired and ready for sleep too).

However, if it's not those easily fixable areas, you may need the help of a behaviorist or veterinary behaviorist to determine what’s causing your dog to vocalize so much at inappropriate times.

This excerpt is from ASCPA which details many issues: Loss of hearing, cognitive dysfunction, central nervous system disorders and medical conditions can all contribute to your dog’s excessive vocalization.. He might whine or howl if he feels the urge to eliminate more, if he’s overeating and wants you to give him more food, or if he’s in pain. If your dog has become more fearful and anxious, he might begin vocalizing at things that scare or stress him, like noises or visitors. Showing your own frustration or punishing your dog for vocalizing can also increase his anxiety and aggravate the problem.

Once any underlying medical problem and cognitive dysfunction are treated, behavioral treatment involves identifying and modifying any of your own responses that might be reinforcing or aggravating your dog’s behavior.