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.
Definition of den. 1  1 : the lair of a wild usually predatory animal. 2  2a (1) : a hollow or cavern used especially as a hideout (2) : a center of secret activityb : a small usually squalid dwelling. 3  3 : a comfortable usually secluded room. 4  4 : a subdivision of a Cub Scout pack made up of two or more boys.