I’ve just read Dr John Medina’s book Brain Rules. He’s a developmental molecular biologist with a wry sense of humour and a teacher’s enthusiasm for helping us understand our brains. The book sets out 12 “rules”, that are really more like a set of observations, all based entirely on peer reviewed research, that give us insights about how our grey matter functions, what it prioritises and, yes, how to get it to work a little better.
John (he’s such a cheery, affable guy you can’t help but want to call him John) starts off by pointing out that much of what the brain is designed to do, and is naturally good at, relates to surviving. Our problem solving ability, combined with our ability to communicate with and understand one another, sets us apart from all our competitors. With a kind of twist on the Darwinian take on who gets to survive and prosper, he argues that in the long run, it’s the strongest brains that survive, not the strongest bodies.
And rule number 1? The brain loves exercise (no surprise there). From the time we descended from the trees we were constantly on the move, in fact it’s estimated our earliest versions walked up to 20km per day.
Why is exercise so good for our brain? Chemicals in the brain greedily consume energy and leave behind electrons that can cause free radicals, which have to be absorbed by the oxygen in our blood. So the more oxygen the brain has the better off it is. How does the brain get more oxygen? By having more blood vessels, and it is exercise that increases and deepens blood vessels.
Researchers studied two elderly populations, one sedentary and one active, and chart 1 shows how the exercisers outperformed the couch potatoes in every aspect measured: long-term memory, reasoning, problem solving, abstract thinking, and more.
Chart 1: exercise helps improve all aspects of brain function
The researchers then examined what happened if the couch potatoes got more active, and their cognitive scores improved over the space of four months. The secret is the exercise has to be aerobic, so something that utilises and strengthens the heart and lungs. The good news is you only need two 30-minute sessions per week to see the benefits.
What’s even more striking is those who exercise more than halve the likelihood of falling victim to dementia and Alzheimer’s disease – see chart 2. Having watched my father in law battle that horrible disease I’m thoroughly convinced that any opportunity to reduce the chance of getting it should be enough to get you off the couch and pulling on the runners.
Chart 2: exercise reduces the likelihood of suffering cognitive decline by more than half
John makes the interesting observation that our brains are more creative when we’re on the move as well, so the best business meetings would be conducted with everyone walking at about 3kph.
Rule 2: sleep is critical (again, no surprises there). Although scientists aren’t exactly sure why we sleep, it’s clear that it’s super important for our overall wellbeing. A lack of sleep can be disastrous for the brain, it reduces our attention span, executive function, working memory, mood, quantitative skills, logical reasoning, and even motor dexterity. For example, in one study a group that needed eight hours’ sleep per night were reduced to four and their performance on memory tests went from the top end of the bell curve to the bottom 9%.
John explains that the body’s Circadian Arousal System and Homeostatic Sleep Drive are in constant battle to either have you go to sleep or stay awake. When they both flat line in the afternoons, usually between about 1:45 and 3:30, is when many people feel a sometimes overwhelming urge to have a nap. And it turns out the best thing we could do is listen to our body’s urges. In one study NASA found that pilots who had a 26-minute nap improved their performance by more than 34% and a 45-minute nap saw the boost last more than six hours.
Another interesting aspect is the role sleep plays in cementing our memories. Research on rats shows that as they sleep their brains go over what they’ve learned that day, up to thousands of times, but if they get woken during that period of consolidation they don’t remember things nearly as well.
Rule number 3: stress can be a killer. Our bodies are programmed to respond to cortisol, the stress hormone, to help us survive the proverbial attack from a sabre toothed tiger – it’s the old fight or flight response. The brain is studded with cortisol receptors and stressed brains are designed not to function in the same way as non-stressed brains. The catch is our brain is built to deal with stress for about 30 seconds at a time, so for short periods cortisol can improve the brain’s function, but if it goes on too long it disrupts the neural network, prevents the hippocampus from making new neurons and even kills brain cells.
Chronic stress hurts memory, concentration, mathematical ability, language processing – almost every kind of learning faculty we have. In fact one study showed extended exposure to stress reduces cognitive performance by as much as 50%.
Rule number 4: multitasking is a myth. As John points out our brain is a sequential processor, and every time you switch tasks the brain has to execute four separate steps. So talking on the phone while typing an email simply means you tire your brain out faster as you ask it to constantly switch and studies show tasks typically take up to 50% longer to complete and contain about four times more errors – see chart 3.
Chart 3: ‘multitasking’ increases error rates four-fold
Even more importantly, this is why talking on your mobile phone while driving is a very bad idea: reaction times are slowed significantly to the point where you’re four times more likely to be involved in an accident.
Boredom: our brains hate being bored, and unless we’re entertained by something our attention span is usually about 10 minutes. So if you’re presenting to an audience you can keep getting their attention back by telling stories or creating events that are stimulating or rich in emotion.
Similarly, our brain’s survival instinct is constantly on the lookout for things it’s familiar with and if it’s seen it before it won’t pay as much attention. Think about that next time you’re doing a presentation: if your slides look the same as everyone else’s you’re likely to lose your audience.
While we’re on presentations, John points out that vision is our most dominant and demanding sense, taking up an estimated 30% of our cortex, so it’s little wonder then that it is also dominant in the formation of memories. Humans are really good at remembering pictures: hear a piece of information, and three days later you’ll remember 10% of it; add a picture and you’ll remember 65%. Food for thought the next time you’re preparing a PowerPoint presentation, as Medina says “Burn your current PowerPoint presentations and make new ones.”
Short-term memory: we forget 95% of what we’ve learned within 30 days and we do the majority of the forgetting within the first few hours. What gets remembered and what doesn’t depends on what ‘kind’ of memory something gets stored in.
Some memories get stored automatically, like your first kiss, because they involve all sorts of stimulus working together at the same time. Others require regular repetition for them to sink in, like passwords or a phone number. Repeating something within the first 30 seconds helps it get stored in your ‘working memory’, but that can only hold about seven items at once. If you don’t keep repeating that information it will never make it to your long-term memory. One tip is the more elaborate you make a memory the more likely you are to remember it. So don’t just try to remember someone’s name, remember something about them too.
Long-term memory: it literally takes years for long-term memories to be consolidated as the hippocampus and cortex engage in a lengthy conversation. The best way to ensure memories are consolidated in the long-term cortex, is to have repeated exposure to the same information at regular intervals. As John says, repeat to remember then remember to repeat.
Overall this is an interesting book for anybody who’s wondered if there are things we can do on a day to day basis to help make the most of our brain. I’ve covered what I thought were some of the highlights, but there are other discussions like the brain differences between genders, and a thought provoking chapter about the effects music has on our brains. One thing John doesn’t talk about which is also critical for our brains is what we eat. Hopefully that will make it to the third edition. I guess the other thing to keep in mind is this book is one scientist’s take on the topic.