Thanks for writing. It's really the heart that wakes me from sleep and then usually within 15 seconds I get the feeling where I know that spasm is going to happen - I believe it's the heart first racing although certainly I agree the heart can race from the anxiety an attack causes. I have mostly partial (in legs/feet) stiff-person. I have seen the "intense pushing out" of the feet in stiff person videos - one that did not have stiff person might not realize the intensity/force of that pushing out feeling - it pulled a muscle one day. Let's hope there is a cure some day!