While cats seem to need about 20 hours sleep a day, kittens are the opposite. I’d be surprised if Gracie and Phyllis have slept for more than 4 or 5 hours day. They just aren’t prepared to let sleep cut into playtime.
When they do finally power-down, they usually find a cat bed and pile in together.

It’s that TURBO-KITTEN thang. They just go until they stop. Then they GO again.