I was fascinated by this research out of U of CA and Stanford U.
"Learning spatial tasks increases the production of new cells in an area of the brain involved with spatial memory called the hippocampus. Sleep plays a part in helping those new brain cells survive."
"Sleep-restricted individuals have a shorter attention span, impaired memory, and a longer reaction time. “Sleep is necessary for general health, but it now appears that the brain needs sleep more than any other part of the body"
I'm a sleeper, I have to have a good 8 hours or I know I am not at the top of my game. Perhaps you have noticed the same thing?
RelentlessImprovement.com specializes in cognitive enhancement substances, but I always tell people - put the basics in place first. Good diet, exercise and a good nights sleep.