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Rule #8 Stressed brains don’t learn the same way. • Your body’s defense system—the release of adrenaline and cortisol—is built for an immediate response to a serious but passing danger, such as a saber-toothed tiger. Chronic stress, such as hostility at home, dangerously deregulates a system built only to deal with short-term responses. • Under chronic stress, adrenaline creates scars in your blood vessels that can cause a heart attack or stroke, and cortisol damages the cells of the hippocampus, crippling your ability to learn and remember. • Individually, the worst kind of stress is the feeling that you have no control over the problem—you are helpless. • Emotional stress has huge impacts across society, on children’s ability to learn in school and on employees productivity at work.

— Brain Rules by John Medina

Rule #7 Sleep well, think well. • The brain is in a constant state of tension between cells and chemicals that try to put you to sleep and cells and chemicals that try to keep you awake. • The neurons of your brain show vigorous rhythmical activity when you’re asleep—perhaps replaying what you learned that day. • People vary in how much sleep they need and when they prefer to get it, but the biological drive for an afternoon nap is universal. • Loss of sleep hurts attention, executive function, working memory, mood, quantitative skills, logical reasoning, and even motor dexterity.

— Brain Rules by John Medina

When people become sleep-deprived, for example, their ability to utilize the food they are consuming falls by about one-third.

— Brain Rules by John Medina

Another study followed soldiers responsible for operating complex military hardware. One night’s loss of sleep resulted in about a 30 percent loss in overall cognitive skill, with a subsequent drop in performance. Bump that to two nights’ loss, and the figure becomes 60 percent. Other studies extended these findings. When sleep was restricted to six hours or less per night for just five nights, for example, cognitive performance matched that of a person suffering from 48 hours of continual sleep deprivation.

— Brain Rules by John Medina

To my knowledge, no birdish moniker has ever been applied to those people who seem to need only four or five hours of sleep. They instead are referred to as suffering from “healthy insomnia.”

— Brain Rules by John Medina

Rule #6 Remember to repeat. • Most memories disappear within minutes, but those that survive the fragile period strengthen with time. • Long-term memories are formed in a two-way conversation between the hippocampus and the cortex, until the hippocampus breaks the connection and the memory is fixed in the cortex—which can take years. • Our brains give us only an approximate view of reality, because they mix new knowledge with past memories and store them together as one. • The way to make long-term memory more reliable is to incorporate new information gradually and repeat it in timed intervals.

— Brain Rules by John Medina

Learning occurs best when new information is incorporated gradually into the memory store rather than when it is jammed in all at once. So why don’t we use such models in our classrooms and boardrooms? Partly it’s because educators and business people don’t regularly read the Journal of Neuroscience.

— Brain Rules by John Medina

the memories you encoded as adolescents bear very little resemblance to the ones you remember as adults, as Dr. Dan, who had the patience to actually do this experiment, found out. Take the physical punishment question. Though only a third of adults recalled any physical punishment, such as spanking, Dr. Dan found that almost 90 percent of the adolescents had answered the question in the affirmative.

— Brain Rules by John Medina

Rule #5 Repeat to remember. • The brain has many types of memory systems. One type follows four stages of processing: encoding, storing, retrieving, and forgetting. • Information coming into your brain is immediately split into fragments that are sent to different regions of the cortex for storage. • Most of the events that predict whether something learned also will be remembered occur in the first few seconds of learning.The more elaborately we encode a memory during its initial moments, the stronger it will be. • You can improve your chances of remembering something if you reproduce the environment in which you first put it into your brain.

— Brain Rules by John Medina

Rule #4 People don’t pay attention to boring things. • The brain’s attentional “spotlight” can focus on only one thing at a time: no multitasking. • We are better at seeing patterns and abstracting the meaning of an event than we are at recording detail. • Emotional arousal helps the brain learn. • Audiences check out after 10 minutes, but you can keep grabbing them back by telling narratives or creating events rich in emotion.

— Brain Rules by John Medina

Whether you are a waiter or a brain scientist, if you want to get the particulars correct, don’t start with details. Start with the key ideas and, in a hierarchical fashion, form the details around these larger notions.

— Brain Rules by John Medina

Emotionally charged events persist much longer in our memories and are recalled with greater accuracy than neutral memories.

— Brain Rules by John Medina

Rule #3 Every brain is wired differently. • What you do and learn in life physically changes what your brain looks like—it literally rewires it. • The various regions of the brain develop at different rates in different people. • No two people’s brains store the same information in the same way in the same place. • We have a great number of ways of being intelligent, many of which don’t show up on IQ tests.

— Brain Rules by John Medina

Rule #2 The human brain evolved, too. • We don’t have one brain in our heads; we have three. We started with a “lizard brain” to keep us breathing, then added a brain like a cat’s, and then topped those with the thin layer of Jell-O known as the cortex—the third, and powerful, “human” brain. • We took over the Earth by adapting to change itself, after we were forced from the trees to the savannah when climate swings disrupted our food supply. • Going from four legs to two to walk on the savannah freed up energy to develop a complex brain. • Symbolic reasoning is a uniquely human talent. It may have arisen from our need to understand one another’s intentions and motivations, allowing us to coordinate within a group.

— Brain Rules by John Medina