Jul 8, 2019

Matthew Walker’s Why We Sleep has been one of the most impactful books I’ve read this year. Was first made aware of the book on Peter Attia’s podcast, and then received 3 independent recommendations to read the book from friends.

I read the book cover-to-cover, and took copious notes. Sharing a summary of these here both as a reference for myself, and in hope that it might move fellow Type-A people to prioritize sleep a little more.

Basic Sleep Patterns

There are essentially three kinds of sleep, which I will quickly highlight to make the rest of this post easier to read:

My sleep pattern through a night as recorded by Fitbit

My sleep pattern through a night as recorded by Fitbit

  1. Rapid Eye Movement Sleep (REM Sleep): This typically becomes more prominent in the early hours of the morning and is reflected in light blue color in the image above
  2. Light Sleep (Stage 1/2 Non-REM Sleep): This is important for physical recovery and for rest. It is represented in the mid-hue blue color in the image above
  3. Deep Sleep (Stage 3/4 Non-REM Sleep): This is important for memory, physical replenishment, and hormonal regulation

Sleep as a catalyst for learning

There have been a number of (well-replicated) studies that show the impact of sleep (specially REM sleep) for learning. I won’t link to the studies here, but will present some of their findings:

  1. Deep sleep helps remove unnecessary neural connections. REM sleep strengthens useful neural connections. If you’re trying to learn and internalize new concepts, getting 7+ hours of good quality sleep is becomes a huge advantage
  2. Deep sleep helps transfer and make safe newly learned information into long-term storage sites of the brain. REM sleep takes these freshly minted memories and begins colliding them with the entire back catalog of your life’s autobiography. I.e, REM sleep tends to be strongly linked to creativity
  3. Practice, with sleep, makes perfect. Offline learning (letting your brain learn while you asleep after practicing through the day) tends to be more effective than online learning (simply powering through the task without sleep)
  4. REM sleep fuels creativity. Deep sleep helps transfer and make safe newly learned information into long-term storage sites of the brain. But REM sleep takes these freshly minted memories and begins colliding them with the entire back catalog of your life’s autobiography

There are a number of studies that demonstrate this. In the interest of transparency — I have not looked at the studies myself, and am assuming that the author has not mis-represented them in his book: