More early morning symptoms-normal panic?

I have been waking up with muscle tremors. I feel fine when I go to bed usually sleep well, but when I wake up my arms and legs are twitching, shaking, sometimes violently, sometimes just so I can feel quivering. When it's real bad I also feel nauseated. This goes on about three hours and then it gradually resolves. I don't feel panicked, short of breath, palpitations, etc. just this muscle twitching and feeling sick. I have been having one or two actually panic attacks every day but they don't seem to coincide with this muscle thing. The twitching or shivering doesn't interfere with normal motion. e.g. I can go for my morning walk without difficulty--except it takes longer to warm up, and I can't go quite as fast.
IS this normal for panic disorder? Or is there something else going on?
Thanks.