What reason could there be for feeling more awake and alert after barely sleeping through a night, getting 3-4 hours at most, while a normal good sleep (without oversleeping) doesn't make me feel that way? I can't sustain sleeping that little long term because it knocks me right out later, but some days when I've had a fitful sleep my brain just feels perfectly clear, no brain fog, no laziness, no competing thoughts, just a single tasking monster of productivity, which I'm not when I sleep normally.

Weird.