@dkelban Good afternoon and welcome to Mayo Clinic Connect! We’re glad you found us. I, too, have afternoon fatigue , but the only pattern I found was that I did too much and just ran out of energy and/or the dog wanted to sleep and wanted me to lie down. Moderate exercise really does help me. Often, if I feel very tired, I’ll go for a walk instead of a nap. Works every time! Does moderate exercise work for you? I never said, but i also have an autoimmune disease. It’s called Clippers—chronic inflammation of my brain. If you would like, there are some discussions on MCTD.
https://connect.mayoclinic.org/discussion/mctd-mixed-connective-tissue-disease/
What else can we help you with?