Book Summary: Why We Sleep

George Peppou
4 min readJan 15, 2022

I suppose (or hope) it’s normal for founders to sacrifice sleep to build a business. It’s definitely been true for me and Vow over the past 2.5 years.

Whether it’s staying in the office trying to get something to work well into the wee hours of the morning or the anxious waking up in the middle of the night worrying about people, money or the incoming impact of global crises — sleep is much often than not disrupted.

I was gifted this book by Imogen at Square Peg after recording our episode of the Square Peg podcast. For a long time it sat near the bottom of a pile of ‘to read’ books.

This was until I had a few days off camping on Fraser Island and was looking for an interesting and relaxing read for a tropical paradise.

The view from the campsite where I was reading (Woralie Creek, Fraser Island)

Losing sleep to build a company is the payday loan of human biology. Taking out a little bit of extra time today in exchange for a lot of long term health and wellness issues. Not a decision that any rational person would make.

1 Paragraph Summary

Good sleep is as close as we will get to a modern miracle drug. From memory to short and long term health, to fitness and recovery, getting good sleep every night drastically improves many elements in life. Why We Sleep covers what sleep is, what advantages it gives, what happens if we don’t do it (lots of bad stuff) and how to sleep well. It makes the very strong case that routinely getting 8 hours of good sleep is amongst most effective way to improve your life.

The counterintuitive evolution of sleep

Evolution selects for creatures with an unusual ability to survive. Surely being unconscious and limp on the ground for a third or more of every day would be a bad thing, right?

Or, looking at it another way, given every animal on earth sleeps, sleep must be really important.

In fact, across the animal kingdom, the less you sleep the shorter your lifespan. Sleep is the most restorative thing you can do for your body and your mind. Being unconscious and limp on the ground is so restorative that it more than makes up for the risks of sleep.

A complex chemical dance

Our brains are filled with a complex chemical symphony which keeps time and orders our bodies to go to sleep and wake.

Two major processes are responsible for this: our circadian rhythm (internal clock) which keeps time internally and the build up of ‘sleep pressure’ based on how long we have been awake.

That ‘sleep pressure’ is the build up of adenosine in our brains. Our good friend caffeine blocks the receptor for adenosine, largely eliminating the sensation of sleepiness. Enough adenosine, combined with the correct phase of our circadian rhythm and the right environment (dark, quiet, safe) brings on sleep.

Once we slip into sleep our brain has two major modes. NREM sleep (deep sleep), a reflective sleep where we sort and store the raw ingredients of new facts and skills— a crucial part of learning. Alongside REM (dream sleep) where we connect these raw ingredients with one another, and with past experiences. This allows us to build an ever more accurate model of how the world works, giving us an ability to create new ideas and better solve problems.

The outcome of all of this is a brain that can better store and recall memories. This includes both ‘standard’ memories (facts, people, places, stories) as well as motor function (undertaking complex actions like surgery).

But it doesn’t end with the brain. Sleep significantly improves performance, time to exhaustion and maximum force are both significantly improved by good sleep prior to exertion.

Then sleep aids significantly in recovery too, reducing inflammation, increasing muscle repair and restores cellular energy stores including your muscle glycogen.

Not sleeping is spectacularly bad for you

Seemingly almost every ‘bad for you’ thing is exacerbated by lack of sleep. From concentration to chronic illnesses, to the general strength of your immune system.

Even a slight loss of sleep crushes our ability to concentrate. Not a great thing at any time in evolution, but much worse now we have built ourselves multi-tonne and individually piloted cars. Worse still, people studied to determine the impacts of fatigue consistently underestimate how badly their performance is impaired.

Take your pick of essentially any disease from neurological and psychiatric conditions (e.g., Alzheimer’s disease, anxiety, depression, bipolar disorder, suicide, stroke, and chronic pain), to essentially every physical disorder (e.g., cancer, diabetes, heart attacks, infertility, weight gain, obesity, and immune deficiency) to general health and lifestyle (e.g. obesity, circulating hormone levels, reproductive health, and cardiovascular health) you can reduce your risk of contracting all of these are ailments by sleeping 8 hours each night.

To finish, let’s make this really practical. Here are twelve simple tips for healthy sleep:

  1. Stick to a sleep schedule
  2. Exercise is great, but not too late in the day. Try to exercise at least thirty minutes on most days but not later than two to three hours before your bedtime.
  3. Avoid caffeine and nicotine.
  4. Avoid alcoholic drinks before bed.
  5. Avoid large meals and beverages late at night.
  6. If possible, avoid medicines that delay or disrupt your sleep.
  7. Don’t take naps after 3 p.m.
  8. Relax before bed. Don’t over schedule your day so that no time is left for unwinding. A relaxing activity, such as reading or listening to music, should be part of your bedtime ritual.
  9. Take a hot bath before bed.
  10. Dark bedroom, cool bedroom, gadget-free bedroom.
  11. Have the right sunlight exposure. Daylight is key to regulating daily sleep patterns. Try to get outside in natural sunlight for at least thirty minutes each day. If possible, wake up with the sun or use very bright lights in the morning.
  12. Don’t lie in bed awake.