Mine sleep pretty deeply, usually just lying around on the sand. They spend so much energy begging all day long that I am beginning to believe I could drive a truck through our living room and they wouldn't notice.
One night I decided to do a water change at night (something like 11pm or so) since I was already wide awake. Buttercup must have been already asleep; because while usually he spends the whole time chasing around my hand, this night he was very groggy, and was rather in a daze! It was pretty comical. Next morning he was chipper as usual and doing his morning wiggle.