Why We Sleep by Matthew Walker

If you’re anything like me, you probably feel as though you haven’t been getting enough quality sleep. Many books I enjoy, like Essentialism, touch on sleep as a fundamental part of a healthy life, but it’s often overshadowed by diet or exercise. Walker argues that it shouldn’t be:

AMAZING BREAKTHROUGH!

Scientists have discovered a revolutionary new treatment that makes you live longer. It enhances your memory and makes you more creative. It makes you look more attractive. It keeps you slim and lowers food cravings. It protects you from cancer and dementia. It wards off colds and the flu. It lowers your risk of heart attacks and stroke, not to mention diabetes. You’ll even feel happier, less depressed, and less anxious. Are you interested?

It may sound exaggerated, but studies show that almost every system in your body suffers when sleep is cut short. After just ten days of sleeping seven hours a night, your brain functions as if you’d pulled an all-nighter. Three nights of “recovery sleep” aren’t enough to fully bounce back. And after nineteen hours awake, your cognitive performance is on par with someone who is legally drunk.

The consequences extend beyond personal health. Drowsy drivers cause more accidents than drunk drivers; sleep-deprived doctors are more prone to mistakes in surgery; even vaccinations are less effective without a full night’s rest.

Much of this may feel familiar — kids acting out after a poor night’s sleep, or noticing how caffeine and alcohol affect rest — but Walker provides the science behind these observations. He explains circadian rhythms, “sleep pressure,” REM and NREM cycles, and how our brain consolidates memories.

The book is divided into four parts: how sleep works, its benefits, the purpose of dreams, and societal sleep issues. While you could read it out of order, I recommend starting from the beginning. Grasping the mechanics of sleep early makes the later sections more compelling.

Walker makes the science accessible. He references many studies — necessary for a research book — but explains them in clear language. It’s not a quick read, you do need to focus, but there’s little overly technical jargon. Compared to other foundational works, like Daniel Goleman’s Emotional Intelligence, which can be dense, Why We Sleep is much easier to engage with.

I will say that some of Walker’s claims feel overstated. At times, he presents findings as conclusive even when the research is still emerging — like the links between sleep and psychiatric disorders. While it’s true that no major psychiatric condition occurs without disrupted sleep (including depression, anxiety, PTSD, schizophrenia, and bipolar disorder), correlation does not equal causation.

Regardless, the book makes one thing very clear: sleep is crucial for our health. I’ll leave you with 12 tips for healthy sleep:

1. Stick to a sleep schedule
2. Exercise is great, but not too late in the day
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 disrupt sleep
7. Don’t take naps after 3pm
8. Relax before bed
9. Take a hot bath before bed
10. Dark bedroom, cool bedroom, gadget-free bedroom
11. Have the right sunlight exposure 
12. Don’t lie in bed awake