2018 has been a good year in terms of great books. Great reads so far this year include Sapiens, Messy Middle, The Courage to be disliked, Subscribed, to name a few. I wrote quickly about some of them on this blog. However, none is more important than Why we sleep.
Here are a few things I learned:
Sleep isn’t like money in the bank. If you over-spend this month, saving up a little more next month will make up the difference. If you lose one quality sleep one night, that ship has already sailed. There is no getting it back. Hence, the notion of staying up late on the weekdays just to make it up on the weekends is false
Without sufficient sleep, amyloid plaques (poisonous to neurons, killing the surrounding brain cells and associated with Alzheimer’s disease) build up in the brain, especially in deep-sleep-generating regions, attacking and degrading them. The loss of deep NREM sleep caused by this assault therefore lessens the ability to remove amyloid from the brain at night, resulting in greater amyloid deposition. More amyloid, less deep sleep, less deep sleep, more amyloid, and so on and so forth
At fault were the two characters, leptin and ghrelin. Inadequate sleep decreased concentrations of the satiety-signaling hormone leptin and increased levels of the hunger-instigating hormone ghrelin. It was a classic case of physiological double jeopardy: participants were being punished twice for the same offense of short sleeping: once by having the “I’m full” signal removed from their system and once by gaining the “I’m still hungry” feeling being amplified. As a result, participants just didn’t feel satisfied by food when they were short sleeping.
When given just five and a half hours of sleep opportunity, more than 70% of the pounds lost came from lean body mass – muscle, not fat. Switch to the group offered eight and a half hours’ time in bed each night and a far more desirable outcome was observed, with well over 50% of weight loss coming from fat while preserving muscle
With a genuine lack of malice, I proceed to inform them that men who report sleeping too little or having poor-quality sleep have a 29% lower sperm count than those obtaining a full and restful night of sleep, and the sperm themselves have more deformities.
Routinely sleeping less than 6 hours a nigh results in a 20% drop in follicular-releasing hormone in women – a critical female reproductive element that peaks just prior to ovulation and is necessary for conception.
One such foreign entity that natural killer cells will target are malignant (cancerous) tumor cells. Natural killer cells will effectively punch a hole in the outer space of these cancerous cells and inject a protein that can destroy the malignancy.
Examining a healthy young men, Irwin demonstrated that a single night of four hours of sleep – such as going to bed at 3AM and waking up at 7AM – swept away 70% of the natural killer cells circulating in the immune system, relative to a full 8-hour night of sleep.
A large European study of almost 25,000 individuals demonstrated that sleeping 6 hours or less was associated with a 40% increased risk of developing cancer.
A chemical called melatonin helps regulate the timing of when sleep occurs. It governs when the race (sleep) begins, but does not participate in it. Our distractions by modern technology and LED lights suppress and delay the rise of melatonin, meaning that our body is told that sleep should start late. Throw in the enforced awakening by virtue of the industrial culture (alarm clock) and we have a recipe for inadequate sleep.
Memories remain perilously vulnerable to any disruption of sleep (including that from alcohol) even up to three nights of learning, despite two full nights of natural sleep prior.
Selectively warming the feet and hands by just a small amount (0.5 Celsius degrees) caused a local swell of blood to these regions, thereby charming heat out of the body’s core, where it had been trapped. The result of all this ingenuity: sleep took hold of the participants in a significantly shorter time, allowing them to fall asleep 20% faster than was usual, even though these were already young, healthy and fast-sleeping individuals
Most controversial and alarming are those highlighted by Dr Daniel Kripke, a physician at the University of California, San Diego. Kripke discovered that individuals using prescription sleep medications are significantly more likely to die and to develop cancer than those who do not
Saying that alcohol is a sedative often confuses people, as alcohol in moderate doses helps individuals liven up and become more social. How can a sedative enliven you? The answer comes down to the fact that your increased sociability is caused by sedation of one part of the brain, the prefrontal cortex, early in the timeline of alcohol’s creeping effects. As we have discussed, this frontal lobe region of the human brain helps control our impulses and restrains our behavior. Alcohol immobilizes that part of our brain first. As a result, we “loosen up”, becoming less controlled and more extroverted.
Your desire and ability to remain conscious are decreasing and you can let go of consciousness more easily. I am very deliberately avoiding the term “sleep”, however, because sedation is not sleep. Alcohol sedates you out of wakefulness, but it does not induce natural sleep.
I have mixed feelings from reading this book. On one hand, I am glad to be enlightened by all the scientific findings on sleep. On the other, I am a bit horrified by what I have done to my body. Nonetheless, I am determined to prioritize sleep more in 2019 and beyond or at least to limit the hard done to my body.
Above are just a few of many great insights that the book offers. I am not doing the book justice, but I hope you spend some time reading this book and gifting it to friends or beloved ones. (I have no connection whatsoever with the author or the publisher. Just a big fan who wants as many to learn about the science of sleep as possible)