Dogs use barking as a means of expression. At night, your dog may react to noises or want to defend his territory.
Sudden whining or yelping at night can be an indication of pain. An under-challenged dog looks for activities, especially in the quiet hours of the night. Stimulate his mind with games and walks during the day to minimize restlessness at night. A comfortable bed or a quiet corner can provide security and minimize nighttime barking. A firm, low-stimulus sleeping place ensures security.