The Hour Between Dog and Wolf: How Risk Taking Transforms Us, Body and Mind

by John Coates

In a more formal experiment, a group of radiologists in Miami measured glucose use by the brain during a verbal fluency task, which required participants to list as many words as possible beginning with a given letter in a short space of time. They found that people performing this simple task drew 23 percent more glucose into their brains than they did when at rest. Disturbingly, a group of psychologists at Florida State, also looking at glucose levels in the brain, found that during taxing mental (as well as physical) activities our glucose reserves become depleted, and this reduces our capacity for self-control. They concluded that allocation of energetic resources during emergencies follows a “last in, first out” rule, according to which mental abilities that developed last in our evolutionary history, like self-control, are the first to be rationed when fuel is low. Muscles, which draw a small amount of glucose when at rest, come to monopolize available resources during physical activity. The preferential treatment of muscles during a fight, or when playing a sport, for that matter, and the rationing of glucose to the brain regions responsible for self-control, might explain why fights so easily run out of control (hockey seems especially prone). Perhaps the same could be said of our self-control when we are working long hours at the office—we tend to snap more easily—or trying to stick to a diet, since the draining of glucose also drains us of resolve.