Why We Sleep by Matthew Walker PhD

As a sleep scientist for over 30 years, Matthew Walker’s excellent book Why We Sleep is an in-depth review of the purposefulness of sleep, and the dangers when we do not get adequate sleep. Walker writes, when a person gets less than 7-9 hours of sleep per night, the human body actually breaks down in a variety of ways. The immune system is compromised, enabling colds and viruses to do their thing. Reparations of injuries are also impacted negatively. Simply put, a lack of sleep takes the body longer to recover from illness and injury, and ultimately shortens one’s lifespan.

Sleep deficits cannot be made up, and sleeping in on the weekends doesn’t help. Lack of sleep contributes to Alzheimer’s disease, mental illness, diabetes, and cancer. In fact, the World Health Organization categorizes night shift work as a probable carcinogen. Drowsy driving is more common than drunk driving and even more dangerous. We are harming teens by forcing them to wake up and go to high school at an hour so damaging to the circadian rhythm of that age group.

Matthew Walker, PhD

“After thirty years of intensive research, we can now answer many of the questions posed earlier. The recycle rate of a human being is around sixteen hours. After sixteen hours of being awake, the brain begins to fail. Humans need more than seven hours of sleep each night to maintain cognitive performance. After ten days of just seven hours of sleep, the brain is as dysfunctional as it would be after going without sleep for twenty-four hours. Three full nights of recovery sleep (i.e., more nights than a weekend) are insufficient to restore performance back to normal levels after a week of short sleeping. Finally, the human mind cannot accurately sense how sleep-deprived it is when sleep-deprived.”

― Matthew Walker, Why We Sleep: Unlocking the Power of Sleep and Dreams

Walker believes sleep is the platform on which diet and exercise rest. Getting 7–9 hours of sleep a night is not some luxury to aim for, but an absolute essential for the brain to process new information and prepare for receiving more the next day.

Matthew Walker, PhD

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