JonR,
A guy I worked for about 20 years ago was a big time roadie. He and his riding buddies came up with this inside joke about "low brain sugar," as in, "yeah, low brain sugar caused me to turn the wrong way and ride an hour in the wrong direction, low brain sugar made me eat three Circle-K burritos," or his best: "We rode into Pedro's South of the Border, deep into low brain sugar, and thought it was the neatest place on earth! We bought hundreds of dollars' worth of souvenirs!"
I asked whether he meant "low blood sugar," but he shook his head. "No, that's different. That's when you bonk. With low brain sugar, you can still ride... it just makes you stupid."
Now he has clinical proof...