Mental performance when physically exhausted

Dan Ariely of Predictably Irrational fame wrote a very brief piece entitled “Squash and Short-Term Thinking.” He extrapolated from his own experience playing squash when out of shape to suggest that perhaps being exhausted “makes people focus on the short-term and ignore the long-term—and this way become more susceptible to making mistakes.”

Well, if Ariely can draw such an overarching hypothesis from a single anecdote, perhaps I can propose something more mundane based on my experience. I have a long, treacherous driveway infamous for trapping FedEx drivers. If the snow is heavy the driveway is plowed. If it is under 3-4 inches I normally shovel the driveway myself. It’s a daunting task that takes about four hours to complete. I usually do it in two or three installments.

When I come in from a stint of shoveling I sit down at the computer, sip some tea, and pull up an arithmetical puzzle that under normal circumstances is a no-brainer. I can go through it as quickly as I can click my mouse. After shoveling, however, I stumble on it, make mistakes and have to start over. It’s a humbling experience.

I assume that part of the oxygen that fuels my brain (it requires about 25% of the body’s oxygen supply) was rerouted to my skeletal muscles during shoveling and that it takes time to get the oxygen flowing full force to my brain again. But whatever the physiological case, I can attest to the fact that I am decidedly mentally subpar after serious physical exertion.

There are, of course, many other circumstances such as stress and emotional upset that have similar or even more serious ramifications. See, for instance, my post on the long-term effects of making decisions when you’re upset.

I’m not going to use the single snow shoveling example to ramble on about the allocation of our physical, ideational, and psychological resources. But it’s important for each of us to know what sorts of things interfere with our peak mental performance.