According to sleep expert Matthew Walker, Director of the Center for Human Sleep Science at the University of California, Berkeley, and author of the book “Why We Sleep”, sleep is the most effective thing we can do to restore our mental and physical health each day.
There is a direct relationship between how well you sleep and how long you live, and almost no one can sleep less than six hours each night without harming their health.
For most people, regularly getting a full eight hours of sleep enhances memory, concentration, creativity, emotional stability, boosts the immune system, improves athletic performance, and helps prevent serious diseases such as cancer and heart disease.
A night without sleep or only four hours of sleep reduced 70% of cell activity.
The difference between good sleep and poor sleep is that the brain’s ability to remember new information decreases from 100% to 60%.
Staying awake for 24 hours is akin to having a blood alcohol concentration of 0.10%, which is above the legal limit for driving in most places.
A night without sleep or only four hours of sleep has reduced the activity of natural killer cells by 70% (which help combat infections and cancer). Notably, the activity of natural killer cells returns to baseline levels after a normal night’s sleep.
Sleep is often not given the respect it deserves. It is usually the first thing people sacrifice to make time for almost everything else, whether for entertainment or work. However, the common belief that “you can sleep when you’re dead” fundamentally harms your health, happiness, and longevity.
For instance, consistently sleeping less than six or seven hours each night can double the risk of developing cancer and may increase the likelihood of Alzheimer’s disease. Sleep deprivation can also contribute to serious mental health conditions such as anxiety and depression.
A crucial lesson from Walker is that if humans could evolve to require less sleep, we would have done so by now. We are most vulnerable and least efficient when we sleep. However, evolution has still maintained our need for eight hours of sleep.
Sleep deprivation can lead to severe metabolic and hormonal consequences. When individuals experience sleep deprivation, their bodies effectively enter a state of malnutrition. “If you have the mindset ‘I’ll sleep when I’m dead’, ironically, life will be shorter, and the quality of that life will be significantly worse as a result,” Walker noted.
One study involving young, healthy men who were only allowed to sleep five hours over five nights showed that their testosterone levels dropped to the equivalent of a man ten years older.
“Five hours a night for five nights will make a man age a decade,” Walker emphasized, noting that this also affects women’s reproductive hormones such as estrogen and progesterone.
Sleep deprivation also leads to cognitive and metabolic decline. A study in which participants were allowed to sleep only four hours over four nights found that those who previously had normal blood sugar levels were classified as pre-diabetic by the end of the trial. This highlights the profound metabolic impact that sleep deprivation can have in a very short time.
Here are some tips to optimize your sleep: get 7-9 hours of sleep; improve sleep efficiency; maintain a regular sleep routine; adjust sleep according to your schedule; time your exercise appropriately; eat on time; manage stress before bed; practice good sleep hygiene; and monitor yourself for sleep apnea.
