Body temperature is regulated by the hypothalamus. The hypothalamus is a section of the brain responsible for hormone production. It is considered the link between the nervous system and the endocrine system.

The hypothalamus not only controls body temperature. It controls energy levels, the sleep cycle, muscular function, circulation, the gut and defense against infection.

Most fibromyalgia symptoms seem to be due to imbalances in the hypothalamus-pituitary-adrenal axis (HPA axis). These three glands work together to control hormone levels. Disruptions in the HPA axis seem to be at the core of fibromyalgia.

Hypothymus strongly linked to fibro. Distorted so body temp can be all over the place
Suggest you go on YouTube look up Dr Raymond Perrin. Explains in detail. I m seeing him in February. Had success in Fibro treatment

I have a fan in my room, and a large hotpad under the sheet under my middle.
But what i find help me the most is how i make my bed and the sheet material.

In general I don't make my bed in the tradtional way. It looks like I don't make it at all.
Ok first i have plush sheets under me. I have the top plush sheet over, and a plush blanket kind of rolled to the side so i can hug it or pull it over if needed.
My kids call it my nest.

I can't sleep in a traditionaly made bed. And my skin just can't stand even cotton when i am trying to sleep

Given all this information, sleeping with natural fibers such as cotton and wool will help a person to cool off if overheated, and warm up if cold. If you can afford them down comforters in winter months also have breathability. Never use microfiber sheets. You will just keep sweating.

Yes it's a tricky one. I often go to sleep with a foot hangiing out of the covers. Sometimes I have woken up feeling cool to find I hsve completely kicked off sheets and all and am just sleeping on top of the sheet. I just have to pull up the covers again and stick the foot out and fall back asleep again.