Do doggy dream?

A dog will circle around before lying down to sleep, as this is an instinct in the wild, where it will trample down vegetation to create his bed.
It will choose longer grass where its presence will be concealed. Temperature also plays a role in the wild where dogs sleep. If it is cold, it will curl up like a ball to conserve body heat. Puppies sleep together to conserve body heat too.
It is common for an adult dog to lie on its side when sleeping, and start moving its legs in the air. The eyelids and whiskers may twitch too at this stage, that indicates deep sleep.
Dogs normally spend longer hours sleeping lightly, however, waking up rapidly and not entering deep sleep.