Well, brain science is pretty clear that the brain uses about the same amount of glucose (energy) all the time, resting or waking. To contrast with for example

Well, brain science is pretty clear that the brain uses about the same amount of glucose (energy) all the time, resting or waking. To contrast with for example your biceps, which will use a lot of energy when lifting something and then scale back down to near-zero. So in terms of energy use, yes, the brain is always going at near full burn.