"I can't feel my arms!"

Now that its not quite so hot Kellie has resumed her habit of sleeping on my arm at night. I sleep on my side with my hand under my head and she curls up on my bent arm. It's starts out quite cozy, she's purring right by my ear, she's warm and cuddly - all seems right with the world. Then, after sleeping for a couple of hours with a 20lb cat on my arm I wake up, but my arm does not. I turn over to the other side, Kellie follows, another couple of hours go by and I wake up again with a "dead" arm, I turn over again and this goes on all night...... I am so happy when she decides to go under the covers and sleep at my feet, it gives my arms a much needed break.