I have the same problems. I've tried all kinds of different remedies. Sleep is only a small part of it seems like, which is really weird. I can try getting 7 hours of sleep, 8 or 9, up to even like 10 or 11 hours, and it seems that sleep is not a function of how I feel the next day unless I got a TERRIBLE night sleep of only like 4-6 hours. Sometimes I wake up refreshed from 7.5 hours, other times I feel groggy after 9.
I'm weary of using coffee to "cure" this problem, not only because I know it's really easy to develop a dependance on caffeine (from experience) but also after the coffee wears off you feel shittier than before, so the choice is to either drink it all day or avoid it altogether.
There's a supplement called ZMA which supposedly helps induce more restful sleep. Melatonin is another one which is actually natural. Stuff like Tylenol PM (diphenhydramine) is crap because although it knocks you out, it gives a groggy hangover the next day.
If you have any luck with this, please do share!