📚 The Book in 3 Bullets

• Stick to a sleep schedule. Go to bed and wake up at the same time every day. Sleeping later on weekends won't make up for a loss of sleep during the week.

• The benefits of sleep are numerous, so getting 7-9 hours of sleep consistently should be a priority in order to be alert, productive, and healthy.

• Sleep is the foundation for health. Without sleep, exercise and diet mean very little.

✍️ My Top Quotes

• Wakefulness is low-level brain damage, while sleep is neurological sanitation.

• Relax before bed. Don't over-schedule your day so that you don't have time left to unwind before bed. Choose a relaxing activity such as reading or listening to music before bed.

• Naps as short as 26 minutes in length have shown improvements in task performance and overall alertness. But make sure not to nap after 3 so your nightly sleep isn't disrupted.

📖 Summary & Notes

• The circadian rhythm is a 24-hour clock within the brain that communicates to every region of the brain and organs in the body when it's time to be awake and when to sleep.

• This circadian rhythm is generated endogenously even in the absence of external light from the sun.

• Not everyone's circadian rhythm is the same. About 40% of people are considered morning people, and 30% of people consider themselves night owls.

• Melatonin helps regulate the timing of when sleep occurs by systemically signaling darkness throughout the organism, but melatonin itself has little influence on the generation of sleep itself, it just initiates the sleeping process.

• Sleep pressure refers to the natural buildup of adenosine in the brain as the day goes on and is flushed out at night. An increase in adenosine means an increase in sleep pressure and will make you feel sleepy.

• Caffeine works by battling with adenosine and latches onto adenosine receptors which helps to prolong the drowsiness feeling.

• REM sleep has identical brain waves to wakefulness, and it is the stage of sleep where dreaming occurs. During REM sleep, the body enters a state of paralysis which prevents us from acting out our dreams.

• Waking brainwave activity is concerned with the reception of the outside sensory world, while deep NREM slow-wave sleep offers a state of inward reflection—one that fosters information transfer and the distillation of memories.

• For memorizing factual knowledge, early-night sleep, rich in deep NREM, is the most important for memory retention.

• Post-performance sleep is crucial to performance. After an athletic event, sleep helps accelerate physical recovery from common inflammation, stimulates muscle repair, and helps restock cellular energy in the form of glucose and glycogen.

• The recycling rate of a human being is around 16 hours. That means that after 16 hours of being awake, the brain begins to fail.

• With a full night of sleep, we have a balanced mix between our emotional gas pedal (the amygdala) and the brake (prefrontal cortex). Without restful sleep, our primitive emotional brain takes over with uncontrollable reactivity.

• Decreased sleep shuts down the memory inbox, and memories are in a much weaker form, evaporating rapidly.

• If you don't sleep the very first night after learning, you lose the chance to consolidate those memories, even if you have "catch-up" sleep soon after.

• Short sleep has been associated with more than 45 percent greater risk of coronary heart disease.

• Inadequate sleep can cause weight gain. Decreased sleep has been linked to lower concentrations of the satiety-signaling hormone leptin and increased levels of the hunger-instigating hormone ghrelin.

• Sleep disruption may increase the risk of cancer development and, if cancer is established, favor its rapid and more rampant growth.

• Alcohol fragments sleep with a brief awakening. Therefore, alcohol-infused sleep is not continuous, nor is it restorative.

• Nocturnal melatonin levels are not only associated with the loss of daylight at dusk but also with the temperature drop that accompanies the nighttime.

  • Having a cold environment to sleep in may improve the quality and quantity of your sleep.

• Heavy use of alcohol robs you of REM sleep and keeps you in the lighter stages of sleep.

Tips for better sleep

• Take a hot bath before bed. The drop in body temperature after getting out of the bath may help you feel sleepy, and the bath can help you relax and slow down so you're more ready for sleep.

• Get rid of any distractions that may prevent you from sleeping. Make sure your bedroom is dark, cool, and gadget-free. Turn the clocks down and don't watch them. Worrying about the time can prevent you from sleeping.

• Daylight is key to regulating daily sleep patterns. Try to get outside for at least 30 minutes each day. Also, use bright lights early in the morning, and non-LED warm lights at night.

• Don't lie in bed awake. If you can't fall asleep within twenty minutes or feel anxious, get up and do some relaxing activity until you feel sleepy. The anxiety of not being able to sleep can make it harder to fall asleep.

• Stick to a sleep schedule. Go to bed and wake up at the same time every day. Sleeping later on weekends won't make up for a loss of sleep during the week.