For the past year I have sporadically had episodes of chills, fever and rigors. Always in the morning with symptoms that always or almost always are the same. Besides being cold I usuall run a fever of over 100 and get a terrible headache that last most of the day. Most of the time its when I have had 6 or less hours of sleep the night before, but not always. Last July I was having an episode at work and they took me up to emergency where I was admitted and tested for it seems like everything under the sun. The next day they sent me home, they were stumped with no answer except to see my primary care physician. I think its tied to the lack of sleep which causes the fever which in turn causes the headache chills and rigors, but why? This morning was the first exception to the rule. Had 8 hours of sleep and was fine until I got cold at work(everyone in the room was cold) and then it began. My temp went up to 100.6 but is now going down and the rigors have stopped. All the doctors so far seems to be stumped. If you can point me in a direction I would really appreciate it.