I get streaks of this several times a year. For the last two months, I wake up after three or four hours in a hot sweat from the neck up and icy legs and feet. On other nights, it's chills all over. I manage to get back to sleep, but the misery inevitably wakes me again. After I've been awake for an hour, the sensation ends and my ever-present migraine begins, though I still get sudden heat-perspiration attacks to my skull throughout the day. (The migraine stops whenever this begins.) I had to get to the eye doctor this afternoon, dragged myself in, and my hair was so wet from feverishness/sweating that she asked me if I'd just been swimming.
I wish I could suggest a solution ... I have none, other than a very hot bath to combat the chills. (Works for me, but I know some patients have a problem with hot baths.) But so you don't feel so isolated, I think many PWC endure this. I'm of an age where hot flashes are a thing of the past ... and these are much, much worse.