My daughter has pain in both her arms. She has had blood work for a muscle problem, lyme titer, emg testing, and other things. Tried advil and aleve that her neuro recommended. Nothing has helped except raising her aed(epilepsy med) which is one also used for pain syndromes.Hers is sometimes worse when trying to sleep, but can also get bad in the afternoon/evening....

I can have this same heavy, painful, pressure arm feeling but it seems to be related to neck misalignment for me. Her brother sometimes has this when he wakes up...So all three of us have the symptom but different ways of it showing...

We have no answers so sorry we are not much help!

It's from putting too much pressure on it, and having it in such a funny position for so long. You sleep with your arm under your pillow don't you? I've been having the same problem. I woke up with bad pains in which ever arm I slept on most that night, and my arm would be really weak. It's probably lack of blood flow, try sleeping without your arm bent upward. Or even under your pillow at all, it helped me a lot. :d