Why We Sleep by Matthew Walker: Book Summary and Key Lessons

Date published
May 23, 2021
Last updated
Jun 6, 2021 12:36 PM

1. Sleep is not one of the life pillars. It is the foundation

Sleep is not the absence of wakefulness. It is far more than that.

People often say, "Sleep is the third pillar of good health, alongside diet and exercise." In reality, sleep is more important and has a direct influence on both diet and exercise.

For example, we will consume more food after not getting enough sleep. People, on average, eat 300 more calories more each day when short of sleep. That's because 2 hormones that control your appetite (ghrelin and leptin) go out of balance after insufficient sleep.

When sleep-deprived, you will also be more likely to eat sugar- and carbohydrate-rich food (cookies, snacks, bread) because your brain starts to prioritize high-calorie meals.

Workout effectiveness is also controlled by sleep. When you are not getting enough sleep, the body becomes stingy about giving up fat. After 5.5 hours of sleep, more than 70% of the weight lost comes from lean body mass—muscle, not fat.

Here is the list of the main functions that sleep does for our body:

  • Heart and cardiovascular system. Sleep controls the blood pressure and the heart rate
  • Sympathetic nervous system. Calms down the brain and removes us from a fight-or-flight state
  • Metabolism. Regulates the level of blood sugar, appetite hormones, and food satisfaction
  • Reproductive system. Controls the level of testosterone (men) and fertility (women)
  • Immune system. Regulates the generation of "killer cells" in our blood that protect us from infections and cancer
  • Genes and DNA. Protects genes from distortion and anomalies
  • …and other functions, including emotion control, memory, learning, and creative abilities.

We are socially, organizationally, economically, physically, behaviorally, nutritionally, linguistically, cognitively, and emotionally dependent upon sleep.

2. Sleep is the main driver for creativity and productivity

REM sleep (the one where we experience dreams) is intelligent information processing that inspires creativity and promotes problem-solving. During this stage of sleep, your brain tests and builds connections between all sorts of knowledge and seeks out the most distant and non-obvious associations.

The commonly heard message to "sleep on a problem" is as accurate as it gets. When solving a complex challenge, almost 60% of the research participants experienced an "ah-ha!" moment after getting a whole night of sleep.

When you are sleep-deprived, you will also select less challenging problems. Your brain will lean towards low-effort tasks (e.g., listening to voice mails) and ignore the difficult ones (e.g., designing a complex project.)

Therefore, if your profession is highly creative, sleep is your best prescription (and the money-maker.)

3. You don't know how sleep-deprived you are when you are sleep-deprived

The most alarming fact is that the human mind cannot accurately sense how sleep-deprived it is when sleep-deprived.

With chronic sleep restriction over months or years, people acclimate to their impaired performance, lower alertness, and reduced energy levels. It becomes the norm.

And the painful truth is, millions of individuals unwittingly spend years of their life in a sub-optimal state of psychological and physiological functioning. They never maximize their potential of mind or body due to their blind persistence in sleeping too little.

Bonus: Techniques to improve sleep

Improving sleep is possible and there are some practices you can start using today. Here are several tips for getting a good sleep from the Sleep Foundation.

⭐12 tips for healthy sleep

  1. Stick to a sleep schedule. Go to bed and wake up at the same time each day. As creatures of habit, people have a hard time adjusting to changes in sleep patterns. Sleeping later on weekends won’t fully make up for a lack of sleep during the week and will make it harder to wake up early on Monday morning. Set an alarm for bedtime. Often we set an alarm for when it’s time to wake up but fail to do so for when it’s time to go to sleep. If there is only one piece of advice you remember and take from these twelve tips, this should be it.
  2. Exercise is great, but not too late in the day. Try to exercise at least thirty minutes on most days but not later than two to three hours before your bedtime.
  3. Avoid caffeine and nicotine. Coffee, colas, certain teas, and chocolate contain the stimulant caffeine, and its effects can take as long as eight hours to wear off fully. Therefore, a cup of coffee in the late afternoon can make it hard for you to fall asleep at night. Nicotine is also a stimulant, often causing smokers to sleep only very lightly. In addition, smokers often wake up too early in the morning because of nicotine withdrawal.
  4. Avoid alcoholic drinks before bed. Having a nightcap or alcoholic beverage before sleep may help you relax, but heavy use robs you of REM sleep, keeping you in the lighter stages of sleep. Heavy alcohol ingestion also may contribute to impairment in breathing at night. You also tend to wake up in the middle of the night when the effects of the alcohol have worn off.
  5. Avoid large meals and beverages late at night. A light snack is okay, but a large meal can cause indigestion, which interferes with sleep. Drinking too many fluids at night can cause frequent awakenings to urinate.
  6. If possible, avoid medicines that delay or disrupt your sleep. Some commonly prescribed heart, blood pressure, or asthma medications, as well as some over-the-counter and herbal remedies for coughs, colds, or allergies, can disrupt sleep patterns. If you have trouble sleeping, talk to your health care provider or pharmacist to see whether any drugs you’re taking might be contributing to your insomnia and ask whether they can be taken at other times during the day or early in the evening.
  7. Don’t take naps after 3 p.m. Naps can help make up for lost sleep, but late afternoon naps can make it harder to fall asleep at night.
  8. Relax before bed. Don’t overschedule your day so that no time is left for unwinding. A relaxing activity, such as reading or listening to music, should be part of your bedtime ritual.
  9. Take a hot bath before bed. The drop in body temperature after getting out of the bath may help you feel sleepy, and the bath can help you relax and slow down so you’re more ready to sleep.
  10. Dark bedroom, cool bedroom, gadget-free bedroom. Get rid of anything in your bedroom that might distract you from sleep, such as noises, bright lights, an uncomfortable bed, or warm temperatures. You sleep better if the temperature in the room is kept on the cool side. A TV, cell phone, or computer in the bedroom can be a distraction and deprive you of needed sleep. Having a comfortable mattress and pillow can help promote a good night’s sleep. Individuals who have insomnia often watch the clock. Turn the clock’s face out of view so you don’t worry about the time while trying to fall asleep.
  11. Have the right sunlight exposure. Daylight is key to regulating daily sleep patterns. Try to get outside in natural sunlight for at least thirty minutes each day. If possible, wake up with the sun or use very bright lights in the morning. Sleep experts recommend that, if you have problems falling asleep, you should get an hour of exposure to morning sunlight and turn down the lights before bedtime.
  12. Don’t lie in bed awake. If you find yourself still awake after staying in bed for more than twenty minutes or if you are starting to feel anxious or worried, get up and do some relaxing activity until you feel sleepy. The anxiety of not being able to sleep can make it harder to fall asleep.