45 pages 1 hour read

John Medina

Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School

Nonfiction | Book | Adult | Published in 2008

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Summary and Study Guide


Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School by John Medina provides 12 rules for how the brain functions and details how those rules can affect everyday life. Medina is a molecular biologist who seeks to filter and refine neuroscientific research in an accessible way. Brain Rules covers topics from stress to sleep while showing how neuroscience can improve quality of life and learning. Each rule is presented in a way that offers practical applications and insight into how the brain functions. Medina creates his rules based on criteria of rigorous testing and replication. Brain Rules is a New York Times bestseller. This guide utilizes the 2014 paperback edition by Pear Press.

Content Warning: This book proposes biological differences in the brains of those assigned male at birth and those assigned female.


John Medina, molecular biologist and private research consultant, compiles decades of neuroscientific research to establish 12 rules for the brain. Medina explains that he is extremely fussy when it comes to research; each rule is based upon experiments that have appeared in scholarly, peer-reviewed journals, the results for which have been successfully replicated in repeat trials. Each rule focuses on a different aspect of how the brain functions. Medina argues that knowing more about how one’s brain works can lead to implementing effective habits that will have a profound effect on one’s life. His rules cover topics such as exercise, stress, sleep, music, and gender. At the end of each chapter, Medina offers practical tips for individuals, schools, and businesses to capitalize on brain functioning. Brain Rules exhibits three core themes: The Evolution of the Brain, Neuroscience and Education, and The Importance of Simple Habits.

In the introduction, Medina shows how the brain has evolved over time and how understanding the brain’s evolution reveals simple habits that can improve contemporary life. He follows the evolution of the brain and its emphasis on survival. Working cooperatively and using symbolic reasoning are intentional processes developed to increase chances of endurance. Chapter 1 explores the role of exercise in cognitive functioning and mental health. Medina asserts that exercise improves brain performance. Humans are designed to move, and incorporating more exercise into one’s daily routine can have lasting effects on both body and brain function. Chapter 2 emphasizes the importance of sleep and honoring one’s sleep cycles and chronotype. While Medina explains that there is no set prescription for how much sleep a person should get, research shows that not enough sleep can be dangerous and reduce cognitive functioning.

Chapter 3 discusses the role of stress on the brain and how it impacts performance. Cortisol has a damaging effect on the hippocampus, which can lead to memory loss and decreased learning. Students who experience large amounts of stress at home underperform at school. In Chapter 4, Medina shows how everyone’s brains are wired differently. Each time a person learns something new, neurons shift, grow, and rewire. Chapter 5 studies how and why the brain pays attention to things. Medina argues that human brains are not capable of multitasking effectively and that attention is determined by memory, awareness, and interest. He recommends schools and businesses break up tasks into 10-minute segments and to use emotional triggering to capture attention.

Chapter 6 explores how the brain encodes and processes memory. Periodic repetition is extremely important for the retention of learning. The brain takes in sensory information and scatters it throughout all its regions; it then puts all the pieces back together to form a learning experience. Medina suggests that replicating the environment of the initial point of learning can aid memory. In Chapter 7, Medina shows how senses play a role in learning and memory. He argues that utilizing sensory integration can lead to better recall. One of these senses is discussed at length in Chapter 8. Humans are hardwired to prioritize visual sensation over all other senses. Medina explains that this has an important evolutionary reason and that humans can take advantage of their propensity for sight by incorporating images into learning.

Chapter 9 dives into the human connection to music. Although musical training does not improve intelligence, it can improve language and listening skills and improve mood. In Chapter 10, Medina shows the differences in cognition between men and women. He explains that it is difficult to separate brain functioning from culture because the two are intrinsically linked. Yet, there are distinct differences in the way chromosomal male’s and chromosomal female’s brains operate, and Medina argues that this is partially due to the influence of genes. For example, chromosomal males learn to cooperate through the establishment of a hierarchy and competition, while chromosomal females cooperate through suggestion and consensus. In Chapter 11, Medina argues that humans are born with a passion for discovery and that this passion can and should be cultivated throughout one’s life. He asserts that the brain rule that trumps all others is the innate curiosity of the human mind.

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