Just as languages can be related back to a common ancestor, so too with the fairy tale.
What were our ancestors trying to pass on through such stories? There must have been warnings, or shared experiences, that were passed on through such archetypal tales. Like dreams, they occupy that territory between the collective consciousness and individual fears and memories.
One of the most common themes in fairy tales is sleeping, often an enchanted or magical sleep. Snow White and Sleeping Beauty are the most famous examples - with the original folk stories much more brutal, and more suggestive, than the Disneyfied versions. Sleep in fairy tales is a mysterious state - suspended between life and death. Take it a step further, where fairy tales turn into myths, and in Greek mythology sleep, the healer, is the twin of death, both children of the night.
Sleep isn't only about the functional hours of rest, it has its own mystery and culture.