I’ve explained the benefits of sleep mostly from a general, intuitive point of view. And using examples. In this chapter, I want to quickly give some more concrete advantages and properties of sleep.


Here’s the list.

  • Better immune system. You get sick less often, or less severely, and recover faster if sick.
  • You stay at a healthy weight. Sleep helps process food. But lack of sleep increases our appetite, mostly towards unhealthy foods.
  • It lowers your risk for serious health problems, like diabetes and heart disease
  • It reduces stress and improves your mood
  • It increases performance in the general sense: both physical and mental exercise
    • You do better at school or work.
    • You think more clearly
    • You can lift heavier weights or exercise longer before getting tired
    • You keep a better posture during the day
  • You become more social and open. You can get along better with people and deal better with setbacks.
  • You think more rationally and avoid injuries. (As I said, drowsy drivers cause many car accidents every year.)


Sleeping has at its core a single purpose: shut down everything we don’t need, so that we can regrow our body. When you sleep,

  • Your muscles grow
  • Your energy reserve refills
  • Any wounds are healed
  • Harmful viruses are dealt with.

But, the most important part is in your brain.

Your brain uses sleep to put all you’ve learned, seen and experienced that day into the long-term memory. It tries to build strong connections between what you already had and what you did that day. Not sleeping enough therefore causes

  • Memory loss
  • Depression
  • Focus problems
  • Retention problems
  • A host of mental issues, really.

But what does your body actually do? It alternates between two stages.

  • REM (Rapid Eye Movement): otherwise called light sleep.
  • NON-REM: otherwise called deep sleep

The first REM sleep stage lasts about 10 minutes, but they get longer and longer after that. (The final one usually lasts an hour.) Your eyelids move rapidly, you breathe faster and heart rate rises. This is the stage where your brain is most active. Dreams are made in New York at this stage!

The non-REM sleep lasts anywhere between 5 to 15 minutes. It has three substages:

  • You’re not really sleeping. Your eyes are closed, but it is very easy to wake you up.
  • Your heart rate slows and body temperature drops. This is basically preparation for deep sleep.
  • Deep sleep. It is very hard to wake you up. If you wake up, you feel weak, disoriented and maybe even sick.

Your body typically tries to wake up during stage 1 of non-REM sleep.

You should see it like this: you close your eyes and tell your body it is fine to go to sleep. Your body prepares REM sleep, performs the REM stage, and then performs a check: “can I wake up?”

If there’s still work to be done, or it’s still dark, it will continue this cycle.

Using an alarm clock therefore increases your chances of waking up at the wrong time. If you wake up from your alarm clock and you can barely open your eyes, you’ve disturbed REM sleep. If you wake up, and you feel even worse than you did before you went to bed, you’ve cut your deep sleep.

That’s why using a rhythm or schedule helps. Your body knows when to stop doing stuff and wake up on its own. It will plan accordingly.

This is also why, if you wake up multiple times during a night, those are usually 60-90 minutes apart. That’s the time it usually takes for a full cycle to be executed.


In fact, I sometimes have to get up much earlier than I’m used to. This is a special occasion. I set my alarm clock, I check the new time, I write it in my notes. This means the new time is burned into my brain.

What happens? I wake up naturally right before that time. Somehow, our biological clock is really strong and can tell the time when we sleep. If you clearly tell yourself when to wake up, your body might just accomodate for that.

Brain waves

In general, we distinguish four “states of mind”:

  • Alpha brain waves
  • Beta brain waves
  • Theta brain waves
  • Delta brain waves

Delta and Theta only happen when you’re asleep. You can read research about them, and you will see just how important and magical sleep is.

Beta waves are present when you’re fully awake and active. Alpha waves happen when you’re awake, but calm and at rest.

When I talked about the “transition” period (in the After-sleep phaser chapter), this is what I’m talking about.

It takes some time to swap some brain waves for another type. About 30 minutes after waking up, you’re gaining more and more Beta waves, but still have your Delta and Theta. You’re still in that “dream” or “subconscious” state.

This is when you are most creative and find the best solutions. This is when you are most vulnerable.

We have a weird situation, as humans. We have incredible potential, but it’s all locked in our subconscious. If you can manage to get into that “dreamlike” state more often, or stay there for longer, it’s like you upgraded your brain to version 2.0.

Sleep is the easiest and most obvious way to do so. But habits, rituals, meditation, leading a generally stress-free and non-attached life, can help take this a step further.

We’re still studying and learning a lot about that subconscious of ours. About why we sleep, the good it does for our body.

But one thing is certain: the easiest way to improve your mental and physical health, is by getting good quality sleep, every night. I’d recommend prioritizing this over everything else, even work.

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