“Why We Sleep” — Thoughts and Synthesis
At first I thought this was an obvious book. I get it: sleep is important. I’ve definitely heard about sleep’s healing / beautifying / restoring / strengthening qualities.. blah blah.
And so when I saw that this was a full-sized non-fiction book, I’m like “what else is there to be said of sleep?!”
Turned out to be pretty interesting.
Have you ever wondered why literally all creatures sleep? Why? If it’s so “useless”, why has this trait survived all the millions of years of evolution? Have you ever thought of why even fish slept? Fish! They have the “unyielding need to swim in perpetuum from birth to death”, yet Mother Nature even dictated them to have to sleep.
When that was pointed out to me, I thought, “huh, true though”. So the point is, Mother Nature wasn’t wrong — we all have to sleep adequately.
NREM and REM Sleep
So your body has 3 different states:
1. Awake: You’re receptive. You’re experiencing and learning about the world around you.
2. NREM Sleep: State of reflection when your raw memories are being stored and distilled.
3. REM Sleep: This is when your brain appears to be awake but your body is sleeping. Apparently evolution outlawed muscle activity during this state to prevent you from acting out your dreams. It takes up 20–25% of our total sleep time.
You dream during the REM state, when you’re “treated to a bizarre associative carnival of autobiographical themes”. This is the state when your brain is integrating and interconnecting the new memories and information with your past experiences, thus building an ever more accurate model of how the world works.
Most of the REM sleep happens during the later cycle of your 8-hour sleep. I.e., if you cut your sleep short, say, to 6 hours night, you’re missing a lot of your well-needed REM sleep.
Memory Magic
Sleep enhances learning — it’s like a “save” button for all the newly created files you composed during the day. Not only does sleep help you retain your memories, it clears your mental space and helps you make room for new memories.
It can even salvage those that appeared to have been lost soon after learning. I kind of relate to this feeling… So I picked up German again after more than two years of hiatus. And sometimes during conversations (in German) with my German friend, random words will come out, and I’d be super surprised because I know that I hadn’t even seen those words in years.
In addition, sleep strengthens “muscle memory” — a term not very aptly named because muscle memory is in fact, brain memory. Training your muscles help you execute a skilled memory routine. But the routine itself, is in the brain.
Another service that sleep does for you is that it helps you to forget as well. Have you ever gotten in a fight with someone, but then the next day you wake up, things feel alright again? Not only does it help you forget troublesome/painful memories, it also wipes out mundane information (e.g. yesterday’s breakfast, the parking spot the other day…).
Just Sleep On It!
Seems like the saying “sleep on it” actually didn’t come out of nowhere. It’s actually quite logical, given the scientific facts.
Sleep (especially REM) recalibrates and fine-tunes the emotional circuits of the human brain. It accelerates our rational control and reins in our primitive impulses. It allows us to make more intelligent decisions.
One example I thought was interesting was that people who have slept adequately the night before tend to pick up more social cues (e.g. others’ facial expressions, tone of voice) better than those who are sleep-deprived.
In other words, consistent good (REM) sleep actually develops your emotional IQ, and helps you regulate your emotions. As the author puts it, “REM sleep is what stands between rationality and insanity”.
So whenever you want to send an emotional text or make a tough decision in the evening, just sleep on it first!
Caffeine & Alcohol
Coffee is probably the most delicious liquid for me in this world under normal circumstances. But based on experience, I can’t drink it after approx. 3pm because otherwise I cannot sleep.
It’s interesting because in this book the author pointed out that one of the reasons why the modern world is so sleep-deprived is because of our hyper-consumption of caffeine, especially when you consume it later in the day.
Caffeine has an average half-life of 5–7 hours! Which means, if you drink coffee at 3pm, by 9pm only half of the caffeine is out of your system. And even “decaf” has 15–30% of the dose of a regular cup of coffee.
Now alcohol. I think it’s popular wisdom that a little alcohol puts you to sleep. Scientifically speaking, it doesn’t. Alcohol basically sedates you out of wakefulness akin to a light form of anesthesia.
Alcohol immobilizes the part of your brain (the prefrontal cortex) that normally controls your impulses. So as a result, we “loosen up” and become more sociable. Then if you add a little more alcohol, it stupefies other parts of your brain, which then makes you feel more sluggish.
If that’s it, then maybe alcohol isn’t so bad… but no! It actually fragments sleep and suppresses REM sleep — i.e. ridding you of all of sleep’s restorative benefits. On a related noted, as REM sleep is paramount for babies/children who are still developing their brains, this is why pregnant/breastfeeding mothers should not consume alcohol.
Further, since sleep is supposed to help you consolidate memory and what you’ve learned during the day, alcohol intake can block that function even days after your learning sessions..! Too bad.
Other Points to Note :
- You can never “sleep back” the sleep you lost
- Afternoon naps are actually normal from an evolutionary point of view. All humans, irrespective of cultures, have a genetically hardwired dip in alertness that occurs in the mid-afternoon hours. I guess this explains why the early afternoon coffee is so damn delicious!
- Sleep helps with better absorption and digestion of nutrients
- It is shown that people like their jobs less when sleep-deprived — unsurprising given the mood-depressing influence of sleep deficiency.
- Ethical deviance and loafing at work (lol) can also be linked to lack of sleep
- Colder temperature helps you fall asleep faster
- Do not take sleeping pills. Like alcohol, they’re sedatives, they don’t induce sleep, they knock you out of wakefulness and paralyze your brain, not to mention other unwanted side effects
- A few more advantages of sleep: lowers food cravings, strengthens immune system, stabilizes your mental state, makes you less anxious, etc.
Overall…
… it was pretty eye-opening to read this because it really reinforces why sleep is so non-negotiable. Although it does put you to sleep quite easily, because there’s just too much scientific jargon in there.
Anyway, so next time someone tells you they can function without sleep, you can legitimately call BS.
Personally, I will still cut my sleep hours every now and then, I know I will continue to waste time and “procrastinate sleep” on my screens before bed. But it’s just always good to do that in an informed manner than not.
—
Disclaimer: All facts are from the book “Why We Sleep” by Dr. Matthew Walker.
