Why We Sleep by Matthew Walker [Infographic + Summary]

Cognitive Neuroscience & Neuropsychology / Wednesday, May 1st, 2019

By reading this summary of Why do we sleep The answer isn’t what you think. by Matthew Walker, you will discover how to sleep better.

About the author

Matthew Walker, PhD is a professor of neuroscience and psychology, Scientific Expert and Director of UC Berkeley’s Sleep and Neuroimaging lab. The laboratory he works for is focused on researching the impact of sleep on human health and disease.

About the book

Why we sleep belongs to the section of Science and Psychology books and more precisely to Neuroscience. It was released on September 28, 2017, and comprises of 368 pages. The book has an Amazon View score of 4.6 out of 5 with a total of 521 reviews to date (April 26, 2019).

Key quote from the book

“Humans are not sleeping the way nature intended. The number of sleep bouts, the duration of sleep, and when sleep occurs have all been comprehensively distorted by modernity.” 

Matthew Walker, Why we sleep

Why We Sleep Infographic:

Infographic of Why we sleep by Matthew Walker book summary. The description follows in the blog post.
Why We Sleep by Matthew Walker, PhD.

Why We Sleep Summary:

The core idea or exploration of the book is that sleep is not an unproductive thing as most of mankind perceives it to be. When we do it, our minds perform such integral functions which are not possible during we are awake. Let’s understand how:

Kinds of Sleep and Sleep Cycle

During a full night’s, our mind transitions between three forms or phases of around every 90 minutes.

Deep Sleep

It constitutes the first 90 minutes. It is like a temporary storage facility for every information you collected during the day, and when you fall asleep, it is the deep sleep that delivers that information to the right destinations in the right amount. So if you stay busy reading magazines or paying attention to those screens and sacrifices your sleep, it is this phase that you lose.

Light Sleep

This phase is like a cleaning service. It erases the work your mind went through during the day and refreshes the mind for new learning. If you go straight to light sleep, your mind does not get to deliver the information to the destinations, and you lose a lot of important information resulting in poor retention. Furthermore, if you wake up early from light sleep, you lose REM sleep.

REM Sleep (Dream)

This phase connects the newly stored information to the previous information. So if you lose it, you risk the proper connection between information and events. Dreams are vital because they function as therapy; without dreams we will suffer from anxiety and PTSD. This is the night phase that is related to the development of creative and emotional insights and transition from despair to hope and normal life leaving anxiety related to the events behind and not the memory.  

Now we know that:

  • Deep sleep phase helps to recall important information,
  • Light sleep phase helps to erase unimportant information,
  • REM sleep phase makes sense of the information and emotions.

So if we do not get a full night’s sleep from 7 to 9 hours, we will remember, learn and understand less and experience confusion and anxiety in all aspects of our life while every aspect of our life suffers. In simple word, we lose all benefits of sleep while sleeping more cannot make up for the lost sleep phases.

Health Aspect:

The book sheds light on a wide range of health benefits of sleep and issues related to a lack of proper sleep. Let’s go through them here:

  • Regularly sleeping less than 6 or 7 hours a night increases the risk of cancer by 50%.
  • After just one night of less than 5 hours, natural killer cells (naturally every day appearing cancer-killing cells in our body) drop by 70%.
  • Sleep is key for numerous functions of the brain and body, including immune function, memory, problem-solving, attention, growth, and the effective and efficient functioning of many organs.
  • Our ability to fight diseases such as cancer and obesity is directly related to not getting enough soothing sleep.
  • Improper sleep increases confusion, anxiety and contributes to improper mental development.
  • Experiments have shown that people who do not take the full night of sleep remember 40% less than the individuals who sleep for 7 to 9 hours daily.
  • Sleep possess the potential to make us healthier, safer, smarter, and more productive if only followed in the right direction.

Ways to Improve Sleep Cycle

There are a number of steps that assist in making your sleep proper and relaxing.

  • Make and stick to a sleep schedule, finish work and go to bed at the same time each day. Your mind will follow that system, and it will be easy to sleep daily on time.
  • Avoid caffeine, nicotine drinks in the afternoon and alcoholic drinks before bedtime as they disturb REM sleep.
  • Refrain from having large meals late at night and heavy beverages.
  • Taking a bath before bed helps by lowering down the body temperature.
  • Dark is good because light and especially blue lights from screen suppress melatonin production required to fall asleep. It is also required to get full sleep and avoid early waking up which will disrupt REM sleep.
  • Do exercise but not too late during the day because it increases the temperature, so no exercise later than three hours before bedtime.
  • Relaxation is key, and it can be achieved by reading good books or listening to soothing music.
  • Refrain from medicines that keep you up as well as the sleeping pills because these only make unconscious and limit REM sleep.
  • Do not lie in bed if you cannot sleep; it will actually delay the sleep and avoid taking a nap after 3 pm.


The book explores the health, emotional, psychological and business aspects of compromising the quantity and quality the sleep that Mother Nature has intended for us and offers insightful counsel as well. The book also shed light on the certain importance of dreams and how they offer therapeutic and problem-solving functions.

The book provides a clear understanding of sleep phases and benefits or issues we get from not following the sleep pattern. Professor Walker has also listed several practical ideas on how to sleep better. We can put immediately to use and experience improvement in both quantity and quality of sleep. However, the book does not offer solutions for patients experiencing serious sleep issues and only offers general guidelines.

The book not only addresses the issues of sleep but also explain the research that discovered the role and significance of sleep in our lives and for our health. If you wish to unravel the sleep mysteries and gain true insight into what actually our sleep and dreams do for us and how and if you want to make your life better by avoiding all the sleep mistakes you make that actually worsen your life, give the book a good read and find practical solutions to issues related with sleep and consequently every aspect of your life.

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