Energy Consumption Of Our Brain

Little known fact, 25% of energy (electricity) produced by our body is used by our brain even though it is only 3-4 lbs.Also, if you concentrate on doing something hard like calculus, solving a hard puzzle you lose the most energy which is used by the brain...at that state you lose as much energy as when you run the fastest...that is why we get tired doing hard mental work.

I point this out because, the people who do mental work, knowledge workers---scientists, doctors, chemists, programmers-- they are actually working harder...that is why they always look weary/fatigued, but people think they do less work even though their brain uses more energy.