Spoiler: It's the most important thing you do...
Types of Sleep
There are two high-level types of sleep: REM and non-REM.
Non-REM sleep is responsible for replenishing your body. In foreign environments, such as hotel rooms, your brain resists falling into deep stages of non-REM sleep as a sort of threat detection.
REM sleep is also known as Dream Sleep. Parts of the brain are often more active during this phase of sleep than when you’re awake. The prefrontal cortex which is responsible for logic and reasoning shuts off during this time. This is why dreams can often seem crazy, with no sense of reason or time. It’s good for your memory and emotional regulation.
Your brain tends to replay learnt things like motor skills, to solidify the neural connections. It also rapidly accelerates and decelerates your cardiovascular system during sleep.
Effects Of Sleep Deprivation
Sleep deprivation can be extreme, or it can be subtle. We in the west believe that six hours per night is not depriving us of sleep, but the evidence suggests otherwise.
As you would expect, going several days without sleep has a catastrophic effect on the brain. When you’re deprived of REM sleep, a backlog builds up and the brain starts to hunger for it. If backed up too far, dream sleep spills into reality, causing delirium and hallucinations.
In 1959, a radio DJ named Peter Tripp attempted to go two hundred hours without sleep. Within three days he had succumbed to paranoia and hallucinations. A scientist studying the attempt came towards him and Tripp ran away into the street, thinking the man was an undertaker coming to bury him.
Many people believe six hours of sleep per night is a perfectly reasonable amount of time. The percentage of people who can survive on six hours of sleep per night without measurable impairment is so negligible, it is statistically zero. ZERO.
Both mental and physical deficiencies are known to occur in people who sleep six rather than eight hours.
Starting with mental impairments:
- Cognitive Function — In Edina, Minnesota, school start times were moved from 7:25 am to 8:30 am. The average SAT scores of the top ten per cent of students before the time change was 1288. After it, the average was 1500. An increase of 212 points.
- Reaction Time — Teton County in Wyoming did a similar thing, moving school times from 7:35 am to 8:55 am. Amazingly, that single change reduced car accidents in Teton County by 70%. Compare that with the introduction of ABS, which was hailed as a revolution in vehicle safety, which was about 20–25%.
- Alzheimer’s Disease — There is a direct link between lack of sleep and the likelihood of developing Alzheimer’s disease in old age. Those who argue “Margaret Thatcher survived her whole career on 4 hours sleep per night” are neglecting the fact that she developed Alzheimer’s disease in later life.
- Dietary Habits — With lack of sleep, the hormones which regulate hunger and fullness almost flip in the worst possible way. Leptin, which tells the brain it is full is dampened, and ghrelin which is responsible for hunger is heightened. You’re also more likely to choose less nutritious foods when sleep-deprived, choosing sugars and carbohydrates over healthier options.
- Judgement — Like a drunk person thinking they’re fine to drive, subjective judgement about how impaired you are from sleep deprivation is a terrible predictor for how impaired you are.
That’s just some of the mental impairments that are known to occur with sleep deprivation. It’s unlikely you’re shocked at much of these since most people are aware that it has some effect on the mind. The physical impairments are far more surprising:
- Reduced Testosterone in Men — Six hours sleep a night is enough to reduce testosterone levels to that of a male ten years senior. This hormone is vital for male virility.
- Physical Exhaustion — Signs of physical exhaustion occur 20–30% earlier with six hours of sleep compared with eight. During exercise, lactic acid builds up in the body. This build-up occurs quicker in the body with less sleep.
- Lung Function — The ability for your lungs to inhale oxygen and expel carbon dioxide decreases.
- Physical Performance — Peak sprint speed, jump height and max weight lifting are all impaired with six hours per night rather than eight. Basic balance is also noticeably impaired.
- Likelihood of Injury — There is a direct correlation between less sleep and the likelihood of professional sportspeople developing an injury throughout a season. Athletes who sleep five hours per night are 60% more likely to develop an injury than those who sleep nine.
- Likelihood of Disease — Less sleep has a direct correlation with the likelihood of developing serious illnesses like cancer and diabetes. Natural Killer Cells which are responsible for hunting and destroying cancer cells drop by 70% after just one night of four hours sleep. One night.
- Heart Attack — Daylight savings is a perfect predictor of heart attacks. When we lose an hour in the spring, the rate of heart attacks increases by 24%. When we gain an hour, they decrease by 21%.
- Stress — Genes relating to stress are more active when deprived of sleep, which goes some way to explaining the heart attack statistics.
How To Improve Your Sleep
There are many ways in which we can improve our sleep by knowing some of the basic biological mechanisms behind it.
Melatonin is the tiredness hormone. It tells the brain and body when it’s time to sleep. When we experience darkness, it spikes. It also spikes when we experience a drop in temperature. It makes sense since both of those things are associated with nightfall. To ensure you have a regular melatonin cycle make sure to:
- Put the screens away — Reading on a tablet delays melatonin by about three hours. Even then, the peak of the spike is reduced by 50% in some cases, resulting in less REM sleep.
- Turn the lights down — In the evening, turn the lights down in the house.
- Regulate temperature — A cooler room in the evenings will signal to the body that it will soon be night time.
- Regularity — This is a key point and one which I struggle with. Everyone has their circadian rhythm and regularity is the key to harnessing that.
- Nap if Necessary — If you know you have lacked sleep, finding time to nap will help. It won’t provide you with all the benefits of a full night’s sleep, but it will help temporarily.
- No Alcohol — Alcohol is known to block REM sleep.
This article was inspired by Matthew Walker, author of “Why We Sleep: The New Science of Sleep and Dreams”