Like others I will say that although sleep has never been restorative since my accident, in the sense that I wake up and am like "Wow! I'm so alert and happy to start my day!" (I used to be one of those annoying morning people), I know that my functioning goes down hill as the day goes on. So I too try to get at stuff right after waking or I'll get lulled into apathy quickly.

I have found that even lying down, (once I consciously made the decision not to get annoyed if I didn't actually fall asleep despite how tired and drowsy I felt), for a half hour or so can help me reset a little bit.

But yes, napping is normal