On average, dogs sleep about 14 hours a day. Larger dogs, such as Saint Bernards, mastiffs and Newfoundlands, sleep as much as 18 hours a day. Puppies, who expend energy growing and learning, sleep for 18 to 20 hours per day.
How much a dog sleeps and when he sleeps are determined by his activity level and environment. A pet dog is likely to sleep more than a dog that has a job, such as a search-and-rescue dog.
A dog has the ability to adjust his sleep patterns to suit what is going on around him. He awakens easily when there is something to do and sleeps when the opportunity presents itself.