For the average human, the brain is about 2% of the total body weight, but uses about 20% of the total fuel (including a lot of glucose).
There is almost always activity in the brain. It doesn’t really “rest.”
The activity can be extrinsic, or “stimulus dependent,” or it can be intrinsic, or “stimulus independent.”
The existence of ongoing or intrinsic activity in the brain was first noted by Hans Berger when he introduced electroencephalography in humans in 1929.
It turns out, intrinsic, or resting state, stimulus independent activity uses almost the same amount of resources (“fuel”) as actual intentional mental engagement.
‘‘Mental work, as I explained elsewhere, adds only a small increment to the cortical work which is going on continuously and not only in the waking state.’’ – Hans Berger.
“Further analyses indicated that performing a particular task increases the brain’s energy consumption by less than 5 percent of the underlying baseline activity” – Raichle et. al
So, there we have it.
To daydream, to delay, to task-switch and to postpone for another day takes the same amount of energy as it does to execute, to choose, to start, to go all in and to create!
