Dogs sleep more than us, but they wake more frequently than we do. How much and when they sleep depends on the level of activity in their environment. A dog living as a pet in the home is likely to sleep more than a dog that works for a living, like a search and rescue dog or a dog working on a farm.
In the colder winter months, some rattlesnake species enter a period of brumation, which is dormancy similar to hibernation. They often gather together for brumation in large numbers (sometimes over 1,000 snakes), huddling together inside underground rattlesnake dens or hibernacula.
Hibernacula, hibernaculum, hibernation site, overwintering site, refugia, den... All of these words are used to describe the places where many snakes spend the cold months of the winter and at times, the extreme heat of summer. Hibernacula can range in form from natural structures such as caves and sinkholes to man-made structures such as foundations, crawl spaces and garages.