This is a blog post about my main takeaways from “Why We Sleep: Unlocking the Power of Sleep and Dreams” by Matthew Walker, what I’ve picked up from Andrew Huberman and other things I’ve learned over the time. This is by no means a scientific article and I’m no way or shape qualified to give medical advice.
What is sleep good for?
Sleep resets our ability to focus, alert and be emotional stable when we’re awake. Basically, it’s the period when the body recuperates itself. It’s also the time when we become actually “smarter”. When we sleep, the brain shrinks and the synapses reset, thus making room for new memories.
What makes us sleep and what does caffeine do?
Melatonin regulates the timing of sleep by signalizing darkness. However melatonin isn’t the generator of sleep. The longer we’re awake the more adenosine will be produced. Caffeine blocks the receptors that signalize how sleepy you are to the brain, because they take the place of adenosine. The caffeine level in your system peaks about thirty minutes after you take it. It remains in your system for five to seven hours until your body merely removes half of it.
Light
Sunlight is a crucial part of our natural rhythm. It’s best to be absorbed raw by being exposed to the sunlight directly (about two to ten minutes in the morning). The effect of sunlight is diminished by half when being absorbed behind a window. The main function of the sunlight is to block the release of melatonin.
How should we sleep?
Apparently the modern way of living has messed with the way we sleep. Nowadays we usually take our sleep at once (during night), but some tribes who weren’t affected by modernity (the Gabra or the San) sleep around seven hours at night while they take a nap between 30 minutes to an hour in the afternoon. The San change their sleeping schedule to a one long block during the winters. Furthermore, people who take a siesta are healthier and have a higher longevity.
Jet lag
Basically the jet propels you to another place way too fast for your body to adapt. Your body looks at the sunlight, specifically from which direction it comes to adapt, since the sunlight is the indicator of the start of a day.
It’s harder to get used to a new time zone when flying eastward than when flying westward. Reason one: The eastward direction requires you to fall asleep earlier than usual. Reason two: Our innate circadian rhythm is longer than one day (depends on the person, usually 24 hours and 15 minutes, but for some people it’s around 26 hours). Flying eastward makes the day much, much shorter.
What’s the effect of sleep on obesity?
Lack of sleep increases the ghrelin, the signal for hunger and decreases leptin, the signal for satiation. In other words sleep itself doesn’t have a direct impact on your weight gain. You can still “game the system” by eating your usual portions.