From "Why Cats Do That" by Karen Anderson:

Why do cats dash madly around the house?

Relax, they don't do this to drive you crazy.

Flying around at speeds up to 30 mph, cats who tear around the house with no apparent stimuli are merely burning off vast quantities of stored energy.

This is perfectly normal feline behavior, especially for a mostly indoor cat who doesn't get enough exercise.

Being nocturnal animals, the house will usually turn into a racetrack at night when cats normally hunt.

-- Robin Palmer