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.
Copperheads are usually solitary except during their mating season. They do hibernate in communal dens, though, not only with other copperheads but also with snakes of a variety of species (including rat snakes and rattlesnakes). In the spring and fall copperheads can be frequently seen during the day, but in the warm summer months they are primarily nocturnal.