Squirrels sleep primarily in nests called dreys, which they build in trees. These nests are usually made of twigs, leaves, grass, moss, and other soft materials, providing insulation and protection from the weather and predators. Tree squirrels often construct their dreys in the forks or crooks of tree branches, typically at least six meters above the ground. In addition to dreys, squirrels may also sleep in natural tree cavities, such as hollow spaces or old woodpecker holes, which provide more shelter and warmth. Some squirrels, especially ground squirrels like chipmunks, create underground burrows where they sleep and hide from predators. In residential areas, squirrels sometimes take shelter in human structures like attics and roof spaces, where they build nests from insulation and other materials. Thus, squirrels sleep either high in trees or underground, depending on the species, safety, and available shelter. Their nests prioritize protection from predators, weather, and proximity to food sources for comfort and survival.