Check out this fantastic article on decision fatigue in the New York Times. It addresses a lot of things I’ve been interested in lately, like blood sugar levels and self-control. I think this is a really useful topic for learning folks to be aware of, because we frequently ask our learners to exert self-control to stay focused and concentrate on the subject matter being taught.
http://www.nytimes.com/2011/08/21/magazine/do-you-suffer-from-decision-fatigue.html