Fatigued but not tired

Is this common with CFS? I'm exhausted but unable to sleep during the day. I don't feel tired, per se. It feels more like physical and mental exhaustion. Does that make sense? Another reason might be because I'm anxious in from having to navigate life with ME?

I do get a bit more energy in the evening, and I know this is common with ME, but I don't know if there's a connection. Ring any bells?

ETA: Every time I ask a seemingly obscure symptom, there are so many people with the same experience! It's pretty wild.