When I saw a link to this article on Facebook, headed 'What Causes Chronic Fatigue'?, I had the typical oh-here-we-go-again response. Decided to read it anyway, and although I might take issue with a couple of things, I was pleasantly surprised!
https://www.iflscience.com/health-and-medicine/what-causes-chronic-fatigue-/all/
https://www.iflscience.com/health-and-medicine/what-causes-chronic-fatigue-/all/