Why We Sleep: Unlocking the Power of Sleep and Dreams
August 15, 2024
4 min read
đź“š arvy's Book Club
arvy's Teaser: Sleep-deprived people make worse decisions, take more risk, and overreact to losses. Sound like any investor you know? Matthew Walker's science shows that sleep is the single most important factor in cognitive performance, emotional regulation, and long-term health — all of which directly affect your investing outcomes. Here's why the best thing you can do for your portfolio might be going to bed earlier.
The Book in 60 Seconds
Why We Sleep (2017) by Matthew Walker is a comprehensive, science-backed exploration of sleep's role in every aspect of human health and performance. Walker — director of UC Berkeley's sleep lab — presents evidence that sleep deprivation impairs memory, weakens immunity, increases disease risk, and destroys emotional regulation. His central claim: sleep is the single most effective thing you can do for your brain and body.
Matthew Walker · 2017 · Science, Health & Performance
Idea 1: Sleep Deprivation Destroys Decision-Making — Including Investment Decisions
Walker's research shows that sleep-deprived individuals exhibit impaired prefrontal cortex function — the brain region responsible for rational thinking, risk assessment, and impulse control. With insufficient sleep, the emotional brain (amygdala) takes over: reactions become more extreme, risk tolerance shifts erratically, and the ability to delay gratification collapses.
For investors, this is devastating. Every bad investing decision — panic-selling, FOMO buying, overtrading — is an emotional decision. And emotional decisions get worse with less sleep. The person who panic-sells during a crash at 2am on their phone is making a sleep-deprived decision with their amygdala, not their prefrontal cortex.
The Investor Lesson
Never make investment decisions when sleep-deprived. Better yet: automate your investment decisions so they don't depend on your emotional state at all. A savings plan that runs automatically doesn't care if you slept 4 hours or 8. The system decides. Not your amygdala. (→ Savings Plan)
Idea 2: Health Is the Foundation — Without It, Wealth Means Nothing
Walker's evidence is stark: chronic sleep deprivation increases the risk of heart disease, cancer, Alzheimer's, diabetes, obesity, and depression. It shortens lifespan. It impairs immune function. And it compounds — each year of poor sleep adds cumulative damage that money can't fix.
The shorter your sleep, the shorter your life.
The Investor Lesson
A CHF 2 million portfolio means nothing from a hospital bed. Health is the prerequisite for enjoying wealth — and sleep is the foundation of health. The best ROI you'll ever get isn't from a stock pick. It's from 8 hours of sleep per night for 30 years. (→ 5 Types of Wealth)
Idea 3: Sleep Compounds Like Interest — Small, Consistent Investments Pay Off
Walker shows that sleep benefits are cumulative: consistent, quality sleep over years produces compounding returns in cognitive performance, physical health, emotional regulation, and longevity. There's no shortcut — you can't "catch up" on sleep like you can't fast-forward compound interest.
The Investor Lesson
Sleep is the DCA of health: small, consistent nightly investments that compound over decades. You can't binge-sleep on weekends any more than you can binge-invest once a year. Consistency — 8 hours every night, CHF 500 every month — is how compounding works. In health and in wealth. (→ Ikigai)
What This Means for Swiss Investors
| Sleep Principle | Investor Application |
|---|---|
| Sleep deprivation = bad decisions | Automate investment decisions. Never trade tired. A savings plan removes emotion from the equation entirely. |
| Health before wealth | The best ROI is 8 hours of sleep for 30 years. You can't enjoy wealth without health. |
| Sleep compounds | Consistency — nightly sleep, monthly investing — is how compounding works. No shortcuts. |
arvy's Take
What holds up: Walker makes an overwhelming case that sleep is the most undervalued health intervention. The decision-making connection is directly relevant: sleep-deprived investors make worse decisions, period. The book pairs perfectly with Housel's insight that behaviour — not intelligence — drives investment returns.
What's missing: Some of Walker's claims have been challenged by researchers for overstating certain statistical links. The book is also 100% health-focused — the investment connections are our interpretation, not Walker's.
What we'd add: The best financial plan has three pillars: automate your investments (savings plan), protect your health (sleep, exercise, nutrition), and don't make decisions when you're tired, emotional, or panicking. Walker covers pillar two. Housel covers pillars one and three.
3 Sentences to Remember
1. Sleep-deprived people make worse financial decisions. Automate investing so your portfolio doesn't depend on your emotional state.
2. Health is the prerequisite for enjoying wealth. The best ROI is 8 hours of sleep per night for 30 years.
3. Sleep compounds like interest. Consistency — nightly rest, monthly investing — is how you build both health and wealth.
Buy the book
English (Amazon) · Deutsch (Amazon)
Also in Book Club: 5 Types of Wealth → · Ikigai →
Sleep well. Invest automatically. Compound both.
Automate your finances so your portfolio doesn't depend on your sleep quality. Quality companies compounding while you rest. From CHF 1/month.
This article was written by Florian Jauch, CFA, Co-Founder of arvy, and reviewed by Thierry Borgeat and Patrick Rissi, CFA.
Disclaimer: This article is for general informational purposes only and does not constitute personal investment advice. Amazon links are affiliate links. arvy is a FINMA-supervised asset manager.
