No idea if this is an autonomic issue or not. My first several years with CFS I always felt weak, insubstantial, and trembly on the inside. It feels the way Star Trek transporters shows a body in the first seconds - like tiny bits and pieces missing all over. I think the high levels of elecytrolytes combined with a beta-blocker control this fairly well. Right now I'm feeling an extreme version of this. It does get worse with cold fronts, but usually not on the day after. The front passed through yesterday, but if anything I'm worse today. I also have the jumps and twitches that tend to follow overexertion for me. Come to think of it, it's been years since they've been this bad when I'm sitting in a chair. It's arms and legs both. When I was finally switched to a seizure med that worked, these mostly cleared up, so I assume they're electrical in nature. Any thoughts or explanations? Among other things, I'd like some idea of the physical cause of this symptom. It's possible that I did too much while feeling so bad the last two days. I didn't do much but didn't spend the day in bed either. I was a better rester before FaceBook came along. EDITED to add: The jerks and twitches I've been talking about are an aggravated Restless Leg Syndrome. Today was the first time I've had them in my arms, but the jerks have gone as high as my shoulders when lying down.