There are actually a few theories on why dogs turn around three times before sleeping, including genetics, instinct and general comfort. Like many other domesticated animals, dogs still retain many of the traits found in their undomesticated ancestors. In fact, modern dogs are believe to be 99% identical genetically to their common ancestor, the wild wolf. Wolves living in packs exhibit many of the same behaviors observed by owners of domestic dogs.

One reason dogs turn around three times before bedding down is because that's what feels right instinctively. Ancestral wolves traveled in packs for a number of reasons, primarily to hunt animals larger than any one wolf could kill on his own. When pack animals lie down to rest, they instinctively form a tight circle to take advantage of their neighbor's body heat. Perhaps dogs turn around three times before bedding down today because the practice has become ingrained after thousands of years. When wild packs of dogs turn around three times in the wild, they may be establishing their territory and orienting themselves within the circle.

Another reason some experts believe dogs turn around three times is to trample down the area for comfort. A pack of wild dogs may decide to bed down on a grassy field, for instance, so the individual dogs turn around three times to force the tall grasses down. Any other hazards or obstructions may also be uncovered when dogs turn around three times. This trampling behavior is often observed in domesticated dogs who use padded dog beds or sleep outdoors routinely.

Some suggest that dogs turn around three times for a different form of comfort. Wolves have been observed digging up the ground as they prepare their bedding sites in the wild. This behavior is more often observed during hot weather, so some have theorized that the wolves are exposing a cooler layer of dirt to gain relief from the heat. Domestic dogs, especially larger breeds kept outdoors, may also be duplicating this behavior in an effort to cool down during hot weather. When dogs turn around three times or more, enough of the cooler dirt may be exposed to provide some relief.