When I was studying math heavily (April to July or thereabouts) I remarked to Donovan Greene during one of our talks that I wasn’t having as many ideas as usual. On a typical workday I’ll have about six important ideas- maybe eight microzens total per day– but while I was studying heavily I was down to about two microzens per day and sometimes no big ideas at all. From this we concluded that it was due merely to exhausting my “mental energy”. Well, what does that even mean? For visualization purposes:
The gray stuff lining the outside is gray matter, and the white stuff which comprises the inside is white matter. The gray matter converts perceptions into information with some kinda magic, and passes this data to the big computer underneath. When you look at the white matter, you should be thinking about breadboards with lots of little wires made of myelinated axons (which perform computations), with these wires immersed in a soup of glial cells (which perform maintenance).
This giant network of self-programming wires requires a ton of electricity, as in 12-15 watts or so. You know when a cartoon guy has that lightbulb appear over his head and he shouts “Eureka!” That’s appropriate, because during that all-red brain state the electrical activity in his head is spiking, and I wouldn’t be surprised if it we were talking more than 50W. Still pretty good for a supercomputer. But if this effort were sustained (thank God it usually isn’t), it would be sufficient to move one of those stationary bicycles. No wonder all of those forced child prodigies get brain hemorrhages.
Gray matter doesn’t appear to have such heavy energy requirements, and it seems to be generally true that people and animals who operate purely on System 1 instincts do not require much sleep. Another important factor is high-quality protein and animal fat- to wit, meat. I have noticed these effects personally, and it simply makes sense: animal meat is fuel for the brain. Carbohydrates and sugars can only help somewhat, but they primarily provide fuel for the body. A diet consisting primarily of potatoes or rice, for instance, will produce a person who is walking around with a constant case of brainfog, operating purely on previously acquired instincts (which is fine if you’re an agricultural type).
I remember when I was trying out the milk+eggs+potatoes diet, which requires eating half a dozen potatoes per day (which I never actually managed- glycemic index matters, apparently), I was simply unable to think. “I” was not around much at all, and the subjective experience was of floating around on clouds and every now and then reappearing in my body to find that my hands had been doing my job just fine without me, like a philosophical zombie.