What Happens to Your Body When You Sleep?

By Dr Ernst
October 20, 2017

Everybody says it; everybody knows it: you’ve got to get enough sleep. 8 hours a day, maybe 9. Definitely no less than 7. It’s drilled into our heads. And for good reason.

Interestingly, sleep is getting even more attention these days. We’ve always realized it’s important to your health, but it’s starting to get more and more specific as to how it is important to your health—and how not sleeping enough is particularly dangerous.

The sleep cycle

There’s a good chance you’ve heard of the “Sleep Cycle.” This is one of the reasons it’s so important to budget a long block of time for continuous sleep. It’s less effective to sleep in short burst (i.e., naps). And the concept of “sleep debt” cannot as effectively paid by taking a nap in the afternoon.

An 8-hour sleep cycle goes something like this:

  • When you first fall asleep, it’s called “N1.” That’s light sleeping, or that sort of twilight stage between sleep and awake. This ideally last 10-15 minutes before moving on to…
  • “N2.” This is where your breathing and heart rate slow and your body temperature drops.
  • At “N3” is when most of the magic happens. Blood pressure drops. Breathing becomes slower. Muscles are relaxed. Blood supply to muscles increases. Tissue growth and repair occurs. Energy is restored. Hormones are released, such as: Growth hormone, essential for growth and development, including muscle development.
  • Most of us have heard of REM, and not just the band. This deepest stage of sleep represents about 25% of your sleeping time and it’s when you dream. It’s sort of the “refill” stage. That’s when your brain and body get the energy recharged.

The whole cycle repeats itself in about 90-minute intervals. You ideally want to go through it several times in a single session.

But the sleep cycle is a relatively old model of what happens when we sleep. It’s a health maxim we’ve relied on and has become a part of our culture—like the 4 food groups or counting calories. And it’s not that it’s wrong, it’s just overly simple.

We’re starting to discover a lot more about sleep. For example, it’s relatively new information that the overall cycle gets longer the more times you go through it, to where you might be having a 120-minute cycle by the time the night is over. Also, REM starts lasting longer than the other stages the later into the night you get. That’s why it seems like most of the time, when the alarm goes off, you’re in the middle of a crazy dream.

Sleep and the brain

During REM, your brain is almost as active as when you’re awake. It’s got a lot going on. Toxicity is often stored in your brain—be it heavy metals, pesticides from non-organic foods, medication byproducts, etc. Your brain uses sleep time to try and clear that out. Interestingly, the way your brain clears toxicity when you’re sleeping is by flooding deep brain tissue with cerebrospinal fluid, which flushes out toxins. And what’s crazy is that your brain cells actually move farther apart to allow the fluid in between them when you’re sleeping!

As we age, we’re more likely to develop a type of plaque on our brain cells. They’re called senile plaques or neuritic plaques and they’re made up of protein fragments that collect in between the brain cells. If you don’t clear them out as they form, you develop dementia or even Alzheimer’s.

Furthermore, while you sleep, your brain files away memories. Imagine how much information you process during the day. You process and record the air temperature on your skin, the sound of traffic, every song you hear on the radio, the annoyance when the car honked at you in traffic, the feeling and taste of drinking hot tea. It’s an enormous amount of information. But during all of that, your husband or wife told you something important. Your boss gave you a new task to finish. Maybe your child took her first step. While you sleep, your brain takes those important memories and puts them somewhere accessible and takes all the non-essential stuff and de-prioritizes it (might send it to the trash or file it away—we don’t know). When you don’t sleep enough, thoughts and memories and sensations get all jumbled up and you get frazzled and stressed and your brain just doesn’t work as well.

Sleep and other biological systems

A lot more slows down than your heart rate and breathing. Your muscles shut down pretty much completely. This allows for healing and building muscle. Your intestines slow down as well—which is why you rarely (if ever) wake up to have a bowel movement. Your liver focuses more on healing itself when you’re asleep rather than detoxification like it does when you’re awake. Your adrenals shut down—which is pretty huge because most of us are in some state of adrenal fatigue most of the time.

One of the most important and interesting things going on while you sleep has to do with your hormones. First of all, you release human growth hormone (HGH). This is an incredibly important and underappreciated hormone that helps your muscles grow (hence the name) but it stimulates cell division and replacement. So you need it just to replace old or damaged tissue throughout your body.

Your body regulates the hormones leptin and ghrelin while you sleep. Leptin suppresses hunger, and it is released when you’ve eaten enough food so you feel full. Ghrelin does the opposite, it’s what makes you feel hungry. When you sleep, your body makes more leptin and less ghrelin. That’s why it’s so common for sleep-deprived people to snack—particularly later at night.

What happens when you don’t get enough sleep?

Just flipping the previous sections on their head… Your brain doesn’t get as much time to detox, so nasty stuff starts to pile up. The pesticides you ate on that non-organic apple. The mold you were breathing in at your old office. The chemicals that leached into your coffee from the plastic lid… and much more.

Plaque builds up in between the brain cells. Signals have a more difficult time traveling between brain cells. Your start to have a harder time remembering people’s names, your appointments, random information that you never usually had any trouble just recalling at a moment’s notice.

Thoughts and memories and sensations get all jumbled up and you get frazzled and stressed and your brain just doesn’t work as well because you’re not giving it enough time to manage memories from the previous day.

Without HGH, cells don’t divide on demand as well, damaged tissue doesn’t replace itself as quickly. You take longer to heal from a disease or injury.

You gain weight as ghrelin levels stay high and leptin levels stay low and you’re ALWAYS hungry.

But here’s the craziest thing—and I saved it for last. When you don’t get enough sleep, your body treats that as an infection. Crazy, right? The immune system goes into emergency response mode and releases cells called cytokines that cause inflammation throughout the body.

If you’ve listened to my show at all before, you know how bad inflammation can be. Inflammation is a modern scourge. It leads to almost every chronic condition we see on the rise in your society today: diabetes, cancer, heart disease, obesity, Parkinson’s, and things like arthritis and allergies.

So all of this is basically just to say—get enough sleep people! It really is more important than you think.

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