I always feel better in the morning, whether I sleep or not (could be because I am a Type A and can temporarily overcome my physical symptoms, knowing that HAVE TO go to work). I start to crash around 10:00am and continue crashing until I go to bed (usually 9:30 or 10:00pm). I am then awake by 1:00 and feeling like a bright-eyed-piece-of-crap (brain awake-body dead). I have read that if your liver is the problem you'll feel worse in the afternoon, and if your adrenals are the problem, you'll feel worse in the morning. I don't know if this is true. I know that I have problems with both.
My fatigue seems highly correlated to my amount of sleep. I am only able to sleep 8-9 hours most nights, but if I somehow am able to sleep 11-12 hours, I temporarily feel noticeably better. Conversely, getting lesser than 7 hours of sleep makes me seriously feel like shit.
Sleep study came back normal though. I'm wondering if the study wasn't accurate enough or the doctor didn't do a good job interpreting it.