I also experience insomnia, if I am asleep by midnight, I might get 6 hours. But oh boy, many nights I either can't sleep at all, or might get 2-3. Then the brain fog is so much worse.
Complicating this is that my physiology does not react to sleep meds in the expected way. Either I get revved up or I just cannot sleep.
So, no sleep studies.

I’m waiting on my sleep study. At first o could fall asleep east but woke up feeling just as tired. Then the stiffness and be pain would start waking me up. Now it’s insomnia and waking up in very couple of hours. I was just telling my husband today, it seems the nights I “sleep” all night the next day are my most tired days.

I had a sleep study done and I do not go into REM sleep. I ended up in the hospital as I crashed for 4 days as I had not slept at all for over 2 weeks. They put me on 2 mg of Clonazepam in combination with 50 mg of Seroquel. Then they upped it to 2 mg of Clonazepam in combination with 100 mg of Seroquel which is what I am still on as long as I get to sleep and the pain does not override my sleep medication.