It seems that I have difficulty concentrating, focusing, thinking when I get too much sleep. For me too much sleep seems to be more than 6 hours sleep. However, if I don't get 7 or 8 hours of sleep then I am tired. If I get 8 hours of sleep then I am not tired, but then I have brain fog, like I'm half awake. I saw a sleep doctor and he didn't think that I had a sleep related problem. Any suggestions would be appreciated.