We hope you love the product we recommend! Just so you know, at no extra cost to you, we may get a small commission for purchases made through links in this post. Your support is appreciated. Enjoy the read!
Want to biohack your way to better sleep?
In the eyes of society, diet and fitness were coveted while sleep was valued the least. Back in the day, those who slumbered on for too long were deemed lazy.
The first step to biohacking your health is to understand how sleep works and the essential role it plays in our well-being.
Let’s start with learning about the 4 stages of sleep!
- Sleep Basics
- Stage N1: Entering Sleep
- Stage N2: Light Sleep
- Stage N3: Deep Sleep
- Stage 4: REM Sleep
- Stages of Sleep FAQs
- 7 Tips for Better Sleep
- Sleep Stage – Pop Quiz!
- Final Thoughts
Now, pay attention because I’m going to give you a pop quiz at the end. Hahah – I’m not kidding. School’s in session!
Typically, we all move through 4 stages of sleep: 3 Non-REM stages and then REM (rapid eye movement).
These stages repeat themselves in what is called a ‘sleep cycle’ throughout the night. It takes about 90~ minutes to complete a cycle. More information about this below!
Before we dive into the nitty-gritty of sleep, let’s start with the basics.
The History & Timeline of Sleep Science
Back in ancient times, people thought our brains completely shut off while we are sleeping. Little did we know that the complete opposite is true.
Based on this Harvard Medical Department’s timeline, here are some of the major scientific discoveries related to sleep throughout history:
Dr. Nathaniel Kleitman, AKA the Father of Modern Sleep Research, opened the world’s first sleep laboratory at the University of Chicago.
His work spanned 70+ years and led to major findings that future researchers base their work on today.
German Psychiatrist, Hans Berger invented the Electroencephalograms (EEG).
A device that measures and records electrical activity in the brain by hooking sensors up to a person’s head. The results are varying lengths of waves in graph form.
With the help of the EEG and continuous research, the original five stages of sleep were established.
Rapid Eye Movement (REM) was coined by Dr. Kleitman and fellow researcher, Eugene Aserinsky.
While monitoring his own 8-year-old son, Aserinsky discovered that during the last stage of sleep our brains were highly active, contrary to popular belief.
Dr. William Dement, a student of Dr. Kleitman, established that sleep is cyclical.
For a healthy adult, a sleep cycle is typically 90 minutes long and repeats itself 4-5 times on average per night.
This is where the 8 hours a night recommendation comes from:
90-minutes X 5 cycles = 450 minutes
450 minutes / 60 minutes = 7.5 hours
Even though scientists have been researching sleep for years now, we still aren’t sure why we sleep! Of course, there are many speculations, but nothing is proven yet.
In the words of Dr. William Dement:
“We sleep in order to not be sleepy.”
What is a Sleep Cycle?
We already learned that a typical cycle is 90 minutes long, but, according to Dr. Michael J Breus, the length of time a person needs to fully rest up is unique to that individual. This is why some people only need 6 hours of sleep per night, while others need much more.
I’ve noticed that I need 9 hours of sleep in order to wake up feeling refreshed, and that’s probably because I have a longer sleep cycle.
Eight hours a night may be the general consensus, but there’s really no magic number. Everyone is different.
Sleep Cycles at Night
A healthy adult with no sleep disorders will cycle through the sleep stages on average 4-5 times a night.
After the first cycle, your brain alternates between REM and NREM sleep in reverse order.
For example, after REM, you will transition back into N3, then N2, then back to N3, then REM. If you wake up, then you’ll start at N1 again.
There’s a positive correlation between REM and N2 – the more REM sleep you have, the more N2 you’ll also get.
You may wake up during the transition period between N2 and REM, but probably won’t remember doing so in the morning.
REM has the opposite relationship with N3 – Deep Sleep. As the night progresses, the longer you’re in REM, the less N3 your body needs.
So, what’s all this N1 and REM stuff?!
Let’s dig deeper, shall we?
Stage N1: Entering Sleep
You feel drowsy.
You crawl into your comfy bed, close your eyes and begin to drift off to sleep. I’m sure we’ve all experienced this before.
For a healthy adult with no sleep disorder, the initial Stage 1 only lasts up to 1 – 7 minutes before you enter Stage 2. This makes up only 2 – 5% of the total sleep time.
Your Brain & Body
This first stage is considered more of a transition period.
You start to let go of the day’s tension and your thoughts begin to slow down yet you’re still aware of your surrounding.
Since your brain still registers sounds, so you can easily get pulled out of this stage by the closing of a door or by the hum of your fridge.
Your heartbeat and breathing recede. Your eyes roll to the back of your eyelids. You part your mouth slightly as your jaw relaxes.
For some people, when they get woken up in this stage, they might even say they weren’t asleep at all.
There are 5 main ones and they’re measured in frequency or cycles per second notated in Hertz (Hz).
It might look like you’re only emitting one brainwave frequency at a time, but you’re actually emitting several at all times. One is just usually more dominant.
Let’s find out how each brainwave is different from one another.
When you’re awake, alert and moving. You could be focused on something complex or trying to make a decision.
High brain activity as hundreds of thoughts are being filtered through your mind.
Most of the time, we’re in Beta.
NREM Stage 1 – Our brains begin to slow down.
You’re relaxed but barely conscious. You’re closing your eyes and ready to fall asleep.
We can daydream or be creative – we usually get our best ideas at this time.
Stage NREM 1 is also when some involuntary body twitches happen, called ‘hypnic jerks’ or ‘sleep start’.
Why it happens is still a mystery but there are some theories.
Don’t worry about it too much because it’s perfectly normal and harmless. Sometimes, I jerk myself awake with my own twitches.
People with poor sleep quality may experience more hypnic jerks.
To reduce hypnic jerks, you can try:
- Cutting out caffeine, alcohol or similar stimuli
- Exercising during the day instead
- Reducing your mental and emotional stress levels
- Meditation or relaxation techniques
Stage N2: Light Sleep
Stage 1 and 2 are usually defined together as ‘light sleep.’ However, Stage 2 is actually when you enter sleep.
Harder to awaken, any movements or noises that would jolt you out of slumber in Stage 1 will show up on the EEG as a K complex, while bursts of brain activity will show up as sleep spindles.
NREM 2 typically lasts up to about 10 – 25 minutes, representing 45 – 55% of your total sleep time.
In this time, you’re less aware of your surrounding, your brain activity continues to slow down and you start to emit more Theta waves.
Your entire body continues to relax.
Your breathing, heart rate, blood pressure, and all metabolic functions slow down even further.
Your eyes stop moving, your body temperature drops.
Most of the night is spent this Stage. For good reason too!
Stage 2 is essential for memory consolidation. According to one study, people who learned something new during the day will have a higher density of sleep spindles than those in a control group.
You are now prepared to enter Stage 3 – the notorious Deep Sleep!
- 20 – 30 minutes – fight fatigue with a power nap. You’ll feel refreshed because you haven’t entered Stage 3 yet!
- 90 minutes – commit something to memory. One full sleep cycle allows your brain to process something new you just learned!