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20 Things We Need to Know About Sleep

“The best bridge between despair and hope is a good night’s sleep.”

Matthew Walker (1973- )

Dr. Matthew Walker is a British Scientist and the world’s renown sleep expert. He has a fantastic book out called “Why We Sleep” and a wealth of knowledge all over the internet from Talks at Google to The Joe Rogan Experience.

After familiarizing myself with some of Dr. Walker’s work, I couldn’t help but to share it with everyone and include it in my blog because sleep is so damn important for learning.

This post will just be a few of the things I’ve learned about sleep, but I highly recommend checking out Dr. Walker’s work for yourself!

I’ll start with this fun fact:

The number of people that can operate of 7 hours of sleep or less without any deficits is zero.

Literally no one can function at their best without a full night’s sleep. Typically people consider 8 hours to be a full night’s sleep, but that can vary by the individual. Even with just missing out on an hour, there are noticeable differences in performance. No one is exempt from this, we are all human beings and sleep is essential for everyone.

Hunter-Gatherer cultures have no sleep problems.

Probably because they don’t have alarm clocks! Really though, if you have an alarm clock that goes off every morning, then you may be depriving yourself of necessary sleep. If we still feel tired when our alarm clocks go off, then we aren’t done with sleep yet. A lot of hunter-gatherer cultures don’t have the temporal restrictions that many modern people do and that gives them the ability to sleep as much as they need.

Beauty sleep is a real thing.

People who sleep more look better! I mean we’ve all heard it at one time or another – we have a bad nights sleep and someone tells us the next day “Geez, you look like crap.” or “You look tired.” The meaning is the same, we don’t look as good as we could. Skimping out on sleep means skimping out on looking good and the sad truth of life is that looking good is more important than most of what we can bring to the table. If we don’t look the part, we are rarely offered opportunities to perform. Get sleep, get opportunities.

Prefrontal cortex activity decreases with lack of sleep.

I talked a little bit about brain anatomy in my post The Brain vs. The Mind (Part 1). The prefrontal cortex is the part of the brain responsible for executive functioning. That’s basically all of our self-regulation and complex decision making. So if we don’t sleep, we lose our ability to regulate our emotions, actions, reponses, as well as discipline and planning for the future. Without a strong prefrontal cortex, we are likely to feel our emotions more strongly which could result in anxiety or higher levels of stress. Everything is harder when we have to fight our amygdala, we should get adequate sleep so our prefrontal cortex can fight that battle for us.

Lack of sleep leads to a higher sensitivity to negative emotion & an increase in impulsive reward seeking behavior.

This goes hand in hand with the last fact. If we don’t have a strong way of regulating ourselves, then we feel our negative emotions more intensely and seek out the easy reward. Unfortunately, most things that are worthwhile are difficult and require delayed gratification. If we aren’t sleeping, it’s hard to thing past the present moment and delaying gratification is less attractive.

Sleeping “hits the save button.”

Moving information from the short term memory to our long term memory happens during sleep and is known as consolidation. We need to consolidate because holding information in our short term memory uses up cognitive load, which can be thought of as our brain’s physical processing power. Sleeping is what resets our cognitive load. As our days go on, we take in more and more information and store it in our short term memory – this is known as acquisition. When we sleep, we move all of that information into our long term memory, which clears up space in our short term memory. This is why it’s important to sleep every day. I talk a little about this in the memory section in my post The Brain vs. The Mind (Part 2).

Simply moving information from short term memory to long term memory is a massive oversimplification of the actual process. I won’t go too in depth here, but it’s helpful to know that only certain kinds of information gets consolidated during certain stages of sleep. There are 4 stages of sleep and they happen in a cycle. Throughout the night, we experience these 4 stages over and over and over until we wake up. An entire sleep cycle last from about 90-120 minutes.

Stage 1 – this is when someone would be moving back and forth between consciousness and sleep. On an EEG, they would be exhibiting alpha waves. They would look pretty drowsy at this point. This only lasts about 5-10 minutes.

Stage 2 – this is when we really start to sleep. Our body releases chemicals that make it difficult to wake up. Our heart rate and body temperature start to decrease. On an EEG, we’d notice k-complexes and sleep spindles. This lasts about 20 minutes.

Stage 3 – We are in pretty deep sleep at this point. We can have dreams at this stage, but the brain isn’t as active on an EEG. The brain would be giving off delta waves. This is also when information consolidation really happens, but not all information is moved to the long term memory. In stage 3, only a certain kind of declarative memory is moved from short term to long term. Declarative Memory holds information regarding facts, things that we “know”, or things that can be “declared as known,” are consolidated and saved for later. Keep in mind, this process just saves the neural pathway, to strengthen them requires practice. Consolidation of declarative memory occurs in NREM (non-REM) sleep if the information is emotionally neural or simple. Once the declarative information is emotionally charged or complex, then our brain uses REM sleep to consolidate that information.

REM Sleep – This is our deepest stage of sleep, but yet our brain is the most active on an EEG. REM stands for Rapid Eye Movement on account of our eyes moving so much during this phase. We do our most intense dreaming here and if we’re woken up during these phase we’ll feel groggy and disoriented. REM sleep is necessary for the body and mind to function properly. REM sleep allows a reset for our cardiovascular systems by lowering heart rate and blood pressure, and restocks our immune systems. Most of the benefits from sleep coming during REM sleep, so don’t be fooled to think short naps are a replacement for long deep sleep. During REM, we consolidate a different type of information – Procedural Memory. This includes the knowledge of how to do things, typically with motor skills. REM sleep is essential for learning how to play an instrument or a sport, anything that requires a knowledge of moving ourselves in a certain way. When we’re in REM, we can brain run through the procedures (fire the specific neural pathways) 30-40 times during one nights sleep! If you’ve read my Active Recall and Space Repetition post, then you know that means we’ve improved that specific skill overnight literally in our sleep! Studies have found that people are about 20-30% better at a skill after a night of proper sleep without any extra practice.

When I was first learning the guitar, I always had trouble learning a song in one sitting. I could never get it perfectly right, but I knew that if I went to sleep, the next day I would be able to do it!! I thought it was my superpower, but after reading a little bit about skill acquisition I know now that brain was practicing those procedures in my sleep over and over again. No wonder I was so much better the next day!

The Sleep Cycle but really simple.

Being awake is low level brain damage.

Our body has this system known as the Glymphatic System which is responsible for cleaning the brain during sleep. It’s similar to the more commonly known, lymphatic system, which is responsible for cleaning the body. The glymphatic system washes away beta-amyloid, which is a protein that builds up in our brains during wakefulness. Too much of this beta-amyloid in our brains will prevent us from firing our neural pathways correctly. It is the main component of the plaque found in Alzheimer’s patients.

Lack of sleep is the most determining lifestyle factor in developing Alzheimer’s.

After learning about how essential sleep is for the brain, it is not surprising. Living is hard work, our brains are doing a lot, and if we don’t give them a break, then we can’t expect them to work well over the long term.

If you know that you have a proclivity toward Alzheimer’s, then I recommend taking your sleep seriously.

It’s a myth that you need less sleep as you get older, adults will always need 8 hours of sleep.

People like to think that as we get older, we need less sleep. After all, you see it all the time! The old people are always waking up early and going to their early bird specials or gardening at odd hours, but what many people fail to consider is what time they go to bed too. Old people tend to wake up earlier because they go to sleep earlier. They don’t need less sleep, their circadian rhythms are just slightly shifted from the norm.

There are many stages of our lives when we circadian rhythms “aren’t normal”, so to speak. Teenagers also have a shifted circadian rhythm! No one knows for certain the reason behind the shifts, but there are a lot of theories. People think we need less sleep as we get older, but that isn’t true – we always need 8 hours.

The teenage brain has a shift in circadian rhythms that should dictate when schools start.

In addition to the older folks, teenagers have a shifted circadian rhythm which causes them to typically sleep and wake later than the average person. After I learned this, I was so surprised that me entire high school education started class at 7:30 am. My brain never really woke up until like 3rd period and now I know why! We should change the schools to adapt to our body rather than use extra energy to adapt our bodies to our poorly informed institutions. Schools shouldn’t start until at least 10 am.

Men who sleep less have smaller testibles and less terstosterone than men who get full night’s sleeps.

As if we didn’t need another reason to take sleep seriously. Men who sleep 5 hours of less per night have smaller testicles than men who sleep 7 or more hours per night. Men who sleep less than 5 hours per night also produces as much testosterone as someone 10 years older than him.

Cutting sleep shrinks your balls and ages your hormonal production by 10 years. Don’t do it fellas. Just sleep.

Women are less likely to get pregnant when sleep deprived.

Skipping sleep doesn’t just mess with men, women have trouble conceiving if their sleep deprived as well. If you’re trying for kids, make sure you’re well rested!

There is a strong connection between lack of sleep and cardiovascular diseases.

Heart attack, stroke, and high blood pressure increases by 24% the day after daylight savings, but in the fall when we gain an hour of sleep we only get a 21% increase. There is a similar profile for car accidents, suicide rates, and federal judge sentencing severity as well. Just a single hour of sleep can influence a lot! Maintaining a consistent sleeping schedule is crucial to a healthy cardiovascular system.

Driving sleep deprived is more dangerous than driving under the influence.

People love to demonize drinking under the influence, but will not think twice about driving sleep deprived. There are multiple reasons for why driving without sleep is worse than driving drunk. Seep depravity lowers our IQ more than alcohol intoxication, so we are literally dumber when we don’t sleep. Additionally, drivers under the influence has slowed reflexes which is dangerous when you are in charge of a 2,000 lbs metal moving moving at 70 mph, but sleep deprived drivers don’t react at all which is way worse. Slow reflexes or no reflexes, which is worse behind the wheel?

Getting a handle on our sleep is difficult because of poor social perception.

The inconvenient truth is that we live in a society that does not value sleep as much as it deserves. People who sleep often are labeled as lazy and are shamed if they need or ask for more sleep. People flaunt their sleeplessness as badges of honor as if it is something to be coveted.

If we want to get control of our sleep as a society, then we need to start rewarding people for sleeping adequately! I try to encourage everyone I know to sleep as much as they need to and shame them for skipping sleep. It’s the opposite of what most people do and I know a lot of people think I’m crazy for it, but sleeping properly is more important than others’ poorly informed opinions of me.

Sleep is typically the first thing people choose to sacrifice when they get busy.

I know many people live their lives this way because things get difficult. It’s easy to think believe that sleep is optional and sacrificing a little bit won’t hurt anyone except maybe ourselves, but the opposite is true. Our bodies will work against us if they aren’t properly maintained, and sleep is essential for that maintenance. People have time for what they prioritize. Make sleep a main priority. Sacrifice something else in order to achieve your goals, don’t be quick to think that trading sleeping for anything is an even exchange. Sleep debt is difficult to pay back and natural will always collect what she is owed.

Blue light from our devices delays and interferes with our sleep.

The blue light from our devices delay melatonin (the hormone that gets us ready to sleep) release by 3 hours and cuts it’s concentration by 50%. Something as simple as exposing ourselves to a blue lights will delay our onset of sleep by 3 hours!

Let’s say we need to sleep at 10, so we stop using our phones and turn off all the lights. Our bodies aren’t going to release melatonin for another 3 hours! We won’t be able to start feeling tired until about 1 am. Those blue frequencies tell our brain that the sun is still out and we should still be up! On top of the later onset of sleep, our REM sleep is of lower quality when exposed to these blue lights during the evening hours.

Many of us know this and many devices have a night mode setting to block out the blue frequencies so we don’t mess with our neural biochemistry too much, but I’m not so sure that night mode works well enough.

Artificial lighting in our homes can interfere with proper sleep.

It’s not just blue light that we are sensitive to (although they affect our sleep tremendously), it’s all light. Keeping lights dim at night signals to our body that it’s nighttime and we should start physiologically preparing for sleep. This lowers our blood pressure, keeps our circadian rhythms in their most natural states, and improves the quality of our sleep.

Alcohol and caffeine really mess with sleep.

Some people like to call some alcohol in the evening a “nightcap” to help them go to sleep but the truth is alcohol doesn’t help us sleep. Alcohol may knock us unconscious, but that is not the same as sleep if we are looking at it from a physiological perspective. Alcohol blocks REM sleep and fragments our sleep throughout the night. The frequent interruptions keeps us sleeping in the first two stages of the sleep cycle and even if we stay asleep, REM is blocked and that is where most of the benefits from sleep are. This is usually why we wake up feeling exhausted after a night of drinking. Alcohol doesn’t induce sleep, it sedates us.

Caffeine is another fun drug to keep in mind when we are thinking about sleeping properly. Caffeine has a half-life of 6 hours, so this means that it takes the body 6 hours to process half the concentration of the caffeine out of the body. Let me put it like this, if we drink a coffee at 6 am, half of that caffeine is still circulating around in my body at noon, and a quarter of it will be there at 6 pm. But most of us don’t just have one coffee, we’ll have one in the morning then one at lunch to get us through that afternoon slump. Let’s say we drink that coffee at 2 pm, that would mean that half of that 2nd cup of coffee is still in our system by 8 pm and a quarter of it at 2 am. We may feel tired, but our brain is still physically dealing with the caffeine and studies have shown that it interferes with sleeping properly. The bottom line is that coffee stay in the brain hours after we drink it, if we don’t want our coffee to mess with our sleep, Dr. Walker suggests drinking coffee 14 hours before bed. Even if we manage to fall asleep with the caffeine in our brains, we will experience a 20% reduction in sleep quality which is equivalent to aging our brains 20 years.

We can induce sleep by lowing our body temperature.

The body needs to drop by about 1°C to start sleeping. There are many ways to make this happen. My favorite is to take a super hot shower before bed. The hot water will make the heat radiate from us when the shower is over and our bodies are way more primed for sleeping. Keeping the room cool when we try to sleep is a great way to help get to sleep faster while increasing sleep quality! This makes sense if we think about it, when the sun goes down, it gets cooler and it’s time to sleep. It’s no wonder why we get tired when we lower the temperature just a little bit.