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What I learned from Dr. Matthew Walker


Let’s start with a question: What is sleep? For sure, it is not just a loss of consciousness for 7-9 hours as some people see it, it’s a much more complex and amazing process that plays a big role in our health and daily lives. Sleep is the most effective thing you can do to reset your brain and body health. In terms of its benefits, sleep as a process, an incredibly complex physiological ballet. Even though our assumption has always been that we evolved to sleep, what if we started off sleeping and it was from sleep that wakefulness emerged? So another way of describing what sleep is, as the price we pay for wakefulness.



In us human beings, all mammalian and avian species as well, sleep is broadly separated into these two main types: Non-Rapid Eye Movement sleep and Rapid Eye Movement Sleep. When you're going through different stages of sleep, the changes in brainwave activity are far more dramatic than those that we see when we're awake. During REM sleep, some parts of your brain are up to 30 percent more active than when you're awake. REM sleep is known as a paradox phase: the brain is very active, yet the body is paralyzed. When looking at the brain waves of a person in REM, it’s hard to know if he is in REM sleep or awake. The only way to know which type we are talking about is checking muscle and eye activity (during REM, horizontal rapid eye movement). Just a few seconds before REM sleep, the brainstem sends a signal all the way down the spinal cord and it communicates with the alpha motor neurons in the spinal cord which control the voluntary skeletal muscles and it's a signal of paralysis: the brain paralyzes the body so that the mind can dream safely. There are only two groups of voluntary muscles that are spurred from the paralysis: the extraocular eye muscles and the inner ear muscle. During REM, the involuntary muscles are active, so we can breathe and the heart can beat. That’s also the reason why men have erections and women have vaginal lubrication during sleep. Non-REM is further subdivided into four separate stages um stages one through four, increasing in their depth of sleep. So stages three and four are called deep non-REM sleep stages.



Another thing people are curious about is, what happens when we fall asleep? When we first fall asleep, we'll go into the light stages of non-REM sleep 1 and 2. Then, we'll start to descend down into the deeper stages of non-REM, so after about 20 minutes we head down into stage 3 and then, into stage 4 of non-REM sleep. When we are awake, the brainwave activity is going up and down 20, 30, 40 or 50 times a second. As we're going into light non-REM sleep, it will slow down to maybe 15-20 and then start to slow down to about 8-10 cycle waves per second. Then as we start to move into stages 3 and 4 non-REM sleep, heart rate starts to drop and all of a sudden, thousands of cells in the cortex all decide to fire together and then they all go silent together. When we're 60 or 70 minutes into the first sleep cycle, we start to rise back up into stage 2 non-REM sleep. Then, after about 80 minutes, we have a short REM sleep period and then back down again into non-REM. We do that repeatedly every 90 minutes (the average for most adults) and the thing that changes is the ratio of non-REM to REM within that cycle, as you move across the night.

The first half of the night, the majority of those 90-minute cycles are made of lots of deep non-REM sleep. The second half of the night, that balance changes and the majority of those 90-minute cycles are made of both, lighter forms of non-REM sleep (stage 2) and increasingly more REM sleep. There is some degree of reciprocity between the sleep states so when we drive one of those up, we often see a change in the other. If we only get our first four hours of sleep, we will mostly get deep non-REM sleep but we will get almost no REM sleep and if we only sleep four hours at the second half of the night, we will be mostly deep sleep deprived and will still get mostly all of our REM sleep. The deep non-REM sleep is a form of natural blood pressure medication, so if we lack that, the next day we're going to see abnormalities in heart rate, blood pressure and blood sugar. On the other hand, growth hormone is more REM-sleep-dependent and peak levels of testosterone happen during REM sleep.





Waking up for brief periods during the night worries a lot of people. People at young ages tend to have typically more continuous sleep but the disruptions get more frequent as we progress with age. At the end of our REM sleep period of the 90-minute cycle, almost everybody wakes up, makes a postural movement (we turn over because we've been paralyzed for so long and the body will like to shift), sometimes we also open our eyes position for a brief period of time. Out of the total time we spend in bed, if 85% or more is spent sleeping, it is considered as healthy sleep efficiency. Quality is as important as quantity: getting fragmented sleep (6-7 times of waking up during the night, for short periods) is also an issue.




People lately are starting to practice the Uberman Schedule. It is a sleep pattern where the person elects to sleep in 90-minute bouts, spread throughout the day and night, in an attempt to get more productivity and reduce their overall sleep need. This schedule seems to be negatively affecting the task performances, physiological outcomes and the quality of the sleep. When you fight biology, you normally lose. And the way you know you've lost is disease, sickness and impairment.



When talking about things that affect a good night's sleep, we have to mention caffeine. You can drink coffee! When it comes to coffee, the dose and the timing makes the poison. You should stop taking caffeine 8-10 hours before you fall asleep. Caffeine is in a class of psychoactive stimulants, so it works through a variety of mechanisms: 1. Dopamine mechanism- dopamine is an alerting neurochemical and caffeine plays some role in increasing dopamine but it's 2. Adenosine mechanism- from the moment that we wake up, this chemical builds up in our brain and the longer that we're awake, the more of adenosine accumulates. So caffeine blocks adenosine receptors.



But, what happens when caffeine is dislodged from the adenosine receptors? The caffeine crash! Caffeine has a half-life and it's metabolized. This half-life is between five to six hours and it's down to a liver enzyme, the cytochrome p450 enzyme. There are two gene variants that will dictate the enzymatic speed with which the liver breaks down caffeine and that's why some people are very sensitive to caffeine and other people aren't. So after the caffeine leaves the system, the brain gets hit with an “adenosine tsunami”.


On the same list of discussion, we got alcohol. Alcohol is in a class of drugs, called sedatives. It sedates the cortex and sedation is not sleep, it’s just a loss of consciousness. Alcohol fragments the sleep during the night so the sleep is far less continuous and when you wake up the next morning you don’t feel rested. It is also potent at blocking your REM sleep which is critical for a variety of cognitive functions, some aspects of learning and memory, emotional and mental health, and lastly, hormonal dysfunction (as we mentioned before, the growth hormone, which plays a big role in repairing tissues and metabolism, is mostly connected with REM sleep.)


What about marijuana? We can break cannabis down into two of its key ingredients: THC (tetrahydrocannabinol) which is the psychoactive part that can get people high, and the CBD, the non-psychoactive component. THC makes people fall asleep better, but if you see the brainwave activity, it’s more like a loss of consciousness that lacks REM. One of the biggest problems with THC is withdrawal dependency. As you start to use THC for sleep, there can be a dependency tolerance so you start to need more to get the same sleep benefit and when you stop using, you usually get a very severe rebound insomnia.


There are also a lot of things that promote more healthy sleep. Two of the main things in the list are exercise and daylight. They are wonderful cues for circadian rhythm alignment and also circadian rhythm reset each day. Then we have melatonin- if your system is working in the correct way, as dusk is approaching that's when melatonin will start to rise, the peak being 1-2 hours before sleep. The only source of melatonin in the brain and body is the pineal gland. Melatonin tells the brain and the body when it's day and when it's night and with that, when it's time to sleep, when it's time to wake. Melatonin supplements don’t seem to be a beneficial sleep aid. Metro analysis told us that melatonin will only increase total amount of sleep by 3.9 minutes on average. The only population where we typically see some benefit and it often is prescribed, is in older adults,65 and older, because as we get older you can have calcification of the pineal gland which means that that gland that's releasing melatonin doesn't work as well anymore. Next on the list is magnesium- people who lack magnesium also have problems falling asleep. (There aren’t many studies on threonate, even though it is considered as the most effective form of magnesium.) The latest studies have also seen this effect of some plants in sleep: valerian root (more like placebo.), tart cherry (increased time of sleep by around 84 minutes and decreased daytime naps.) and kiwi fruit- (skin seems to be helpful too. Helps you sleep faster and spend more time asleep.).



Prescription sleep aids are not recommended for long periods of time, only in situations of short term sleep issues.

People wonder whether or not they should take naps. Naps can have some really great benefits for cardiovascular health, blood pressure, levels of cortisol, learning, memory and also emotional regulation. Naps can be anywhere between 20 and 90 minutes. The reason that naps can be potentially dangerous is that when we nap, we risk our sleep quantity and quality at night. Is there a thing like sleeping too much? Yes there is! Hypersomnia is when people have either a very high sleep need or are very sleepy during the day, usually in cases with depression. These people are sometimes staying longer in bed but not sleeping the whole time. People sleeping 10-11 hours usually have poor quality sleep which makes them sleep longer to compensate for that.


A taboo topic that hasn’t been discussed much, is the effect of sex, orgasm and masturbation on sleep. The increased levels of oxytocin and prolactin during sex and masturbation ending in orgasm, contribute to the sleep. Sleep deprivation affects hormones, testosterone and estrogen (ex. Women in night shifts seem to have irregular menstrual cycles.) Sleep can also have a dramatic effect on people’s relationships. Couples who don’t get enough sleep, tend to get more into fights and conflicts. Want some extra tips from the sleep Guru? You got them! 1. If you didn’t have a good night of sleep, the advice is: DO NOTHING! Do not try to make it up for the day. Try following the normal schedule.

2. Hold on to a routine.

3. Don’t count sheep!

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