This book changed my ideology on sleep. Prior to this, I was drinking 2-3 cups of coffee a day (often expresses), getting into bed at 2 am and waking up at 7 am. I thought I was a warrior but in fact, I was a sleep-deprived zombie. The amount of time you sleep is like putting money in a bank account. Whenever you don’t get enough, it’s withdrawn and has to be repaid. When you’re in chronic sleep debt, you’re never able to catch up.
I think that anybody who reads his book will be convinced of the importance of sleep and will make sure that they do all they can to get eight hours.
It scared me into sleeping more.
Sleep deprivation massively reduces our ability to concentrate. In addition to slower reaction times, when tired we lapse into “micro-sleeps” during which we’re totally unresponsive. Walker emphasises that tiredness is a far bigger cause of traffic accidents than drunk driving, that drivers systematically underestimate how tired they are, and that drivers who micro-sleep often don’t brake at all before collisions.
After sleep deprivation, the responses of the amygdala (responsible for strong emotions) can be amplified by over 60%, due to weakened links between it and the prefrontal cortex (responsible for “rational” decision-making).
In the long term, sleep deprivation increases the risk of Alzheimer’s (since toxins are flushed from the brain during sleep), heart attacks (by provoking a stress response from the sympathetic nervous system and raising blood pressure) and cancer (by devastating the immune system). All of these seem to be very big effects – e.g. sleep-deprived patients are twice to three times as likely to suffer calcification of their coronary arteries.
If the above does not scare you I do not know what will. But, the main thing I learnt from this book to analyse how my time was spent. I would have made the argument that I was up late because I was doing something “productive” but I found so many moments of inefficiency. In fact, I now find that I am doing more in less time and sleeping better
Here are some interesting facts about our sleep:
- Human sleep consists of cycles lasting about 1.5 hours, each of which contains first a period of NREM (Non-Rapid Eye Movement) sleep, then a period of REM sleep. In brain scans, the former consists of slow, deep brain waves, while the latter shows the same frenetic activity as an awake brain. As the night goes on, cycles feature a higher proportion of REM sleep. This means that if you cut your sleep short by 25%, you’re actually missing out on somewhere between 60% and 90% of REM sleep.
- There’s a very strong link between NREM sleep and memory. The formation of long-term memories suffers if we don’t get enough sleep (even several days after the events we want to remember). This is true both for memories about facts and experiences and for “muscle memory” of actions like playing an instrument. When sleep-deprived, we also have worse short-term memory. Not to forget REM sleep which, is important in emotional regulation and creativity.
This recap would be lacklustre if I did not share some of the key takeaways on how to sleep better
- It’s best not to drink alcohol in the evenings as it a suppressor of REM SLEEP & stays in your system for hours
- Avoid using screens in the hours before bed, or at least phase out the blue light (e.g. using flux).
- Caffeine has a half-life of 5 to 7 hours, so if you drink it in the afternoon, a significant amount will still be in your system at bedtime. I am to have coffee no later than midday
Bedroom 2 Boardroom 🚀 