Three Brain Rules You Need to Know

(Editor’s note: This article is from a past issue of Brain World magazine. If you enjoy this article, please support us with a print or digital subscription!)

Dr. John Medina is a molecular biologist, private consultant, professor, director of the Brain Center for Applied Learning Research, and, most recently, best-selling author, thanks to the runaway success of his book, “Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School.” Medina, who calls himself a “grumpy scientist,” wrote the book out of a desire to popularize what has been scientifically proven about the brain while dispelling popular myths.

“The good thing about scientific empiricism is that you can turn a guess into actual data,” says Medina. “You might have thought that people want to take a nap, but until you actually measure what the brain is doing when it wants to down-cycle in the mid-afternoon, it must remain in the realm of anecdote. I wrote “Brain Rules” because I got tired of hearing so much anecdote. There are too many mythologies out there, like ‘You only use 10 percent of your brain’ — that’s a myth; ‘There are right- and left-brain personalities’ — that’s a myth; ‘If you play Mozart to your baby when you’re pregnant, it’ll come out as a math genius’ — that’s a myth, too.”

“Most of the stuff we do know about the brain has only been around for 10 years,” he explains. “Because we know, the moral exigency is now on us. We know the brain’s evolutionary performance envelope. Here it is: The brain appears to have been designed to solve problems in an outdoor setting in unstable meteorological conditions, and to do so in near-constant motion. That’s what the brain is good at doing.”

Medina believes that society needs to reevaluate its institutions in the light of these new insights. “If you want to design an education system that is diametrically opposed to what the brain is naturally good at doing,” he says, “you would design a classroom.” When we asked if he was trying to influence social policy, he replied, “The first step in influencing policy is data. This book is a call for brain scientists, education scientists and business scientists to get together and do experiments that could become prescriptive. Once those studies are in place, the policy almost forms around itself.”

To help us to set the policies for our daily lives, we asked Medina to choose the three brain rules he thinks are most important to the average person. Without hesitation, he answered: exercise, stress, and sleep.


“Exercise is extraordinarily important for executive function. When I talk to business audiences, I say that executive function allows you to design a satellite: It’s good for attention to detail, problem-solving, and mathematics. But it’s also what will keep you from punching your boss in the nose if you get a bad performance review. Executive function is involved in planning, foresight, and impulse control.

“We know that you can increase executive function simply by aerobically exercising as little as three times a week for 30 minutes. It’s actually very specific. Toning exercise doesn’t give you a boost in executive function. Lifting weights doesn’t either. The data is so strong, we even know where the sweet spot is: Executive function starts to fly about an hour after a standard workout.

“A group of Siemens engineers were going to open up an office in China, and were learning Mandarin. They got a 22 percent increase in the rate of vocabulary acquisition if, right after their students exercised, they sat them down in the class — as opposed to control groups who had no exercise, or had exercise but did their learning in the evening. That’s extraordinary.

“In a knowledge-based economy, where executive function is one of our most important cognitive gadgets, every think tank on the planet ought to have not cubicles but a powerful set of treadmills. The business uniform shouldn’t be a suit and tie, it should be gym clothes. You should have a guided workout punctuated with meetings, emails, and work. Right now we invert that: We work, and you can exercise on your own time. We have it backwards.

“You might have very good parents and start out with a lot of genetic horsepower. But if you become sedentary, you aren’t nearly as likely to mobilize it. There’s a specific chemical reaction that occurs in the brain when you do aerobic exercise. If you’re exercising, you increase the cerebral blood flow to the dentate gyrus, and you will produce ‘miracle grow’ for the brain — a protein called brain-derived neurotrophic factor, BDNF. The bottom line is that anybody can benefit from that, from smart guys to not-so-smart guys.

(Editor’s note: This article is from a past issue of Brain World magazine. If you enjoy this article, please support us with a print or digital subscription!)


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