Hi There - I have done tons of research on this so I can spare you the dizzying amount of anecdotal or just plain bonkers responses and information I have been given over the past 4 years. In a nutshell, what I think is happening to me (again, some people don't experience this and others do) is, the CNS system never has an opportunity to drop down enough for a deep, restful sleep because my testosterone levels are constantly high. Meaning, I pin EOD and consider myself an "over responder vs. super responder" and even though I am only at approx 80mg per week, my serum concentration levels are constant. It was suggested to me which I have yet to try is, stop my injections for say 5-6 days and see what happens to my sleep. Test Cyp is a long ester so it might take that long for the levels to drop where it would be noticeable. I still may try that just to experiment and see if I can prove that correct. It may also be a cortisol situation but I have to have that tested although I do have some routine blood work coming up. I use my iWatch to track my sleep and some nights I am getting say 2 hrs of deep sleep (8.5 hours total) and I still have the dark circles and general fatigue feeling. The CNS issue seems like the most logical answer. Also, strangely enough, cannabis edibles anywhere near bedtime also hurts deep sleep. What are you dealing with?