Why We Sleep: Unlocking The Power of Sleep & Dreams
Author: Matthew Walker
10 Key Insights:
Sleep enhances your memory and makes you more creative. It makes you look more attractive. It keeps you slim and lowers food cravings. It protects you from cancer and dementia. It wards off colds and the flu. It lowers your risk of heart attacks and stroke, not to mention diabetes. It helps you feel happier, less depressed, and less anxious!
The recycle rate of a human being is around sixteen hours. After sixteen hours of being awake, the brain begins to fail. Humans need more than seven hours of sleep each night to maintain cognitive performance. After ten days of just seven hours of sleep, the brain is as dysfunctional as it would be after going without sleep for twenty-four hours. Three full nights of recovery sleep are insufficient to restore performance back to normal levels after a week of short sleeping.
Two processes determine when we feel sleepy – a 24-hour circadian rhythm where the body is naturally awake for 12-16 hours and a chemical called adenosine that slowly builds up starting from the moment we wake and continues to build until it makes us feel very sleepy at night.
Chronotype, largely determined by genetics, determines your circadian rhythm. Everyone has a different circadian rhythm. For some people, their peak of wakefulness arrives early in the day, and their sleepiness trough arrives early at night. These are “morning types,” and make up about 40% of the population. These people tend to wake around dawn and are happy to do so and function optimally at this time of day. Other people are “evening types” and account for about 30% of the population. These people prefer going to bed late and wake up late the following morning. The remaining 30% of the population is somewhere between a morning and evening type.
First half of the night’s cycle is dominated by Non-REM sleep and the second half is predominantly REM sleep. Waking up 2 hours early may seem like you are only losing 25% of sleep. In reality you might be losing 60-90% of your REM sleep.
During REM sleep, the stress triggering chemical Noradrenaline (brain equivalent of adrenaline) is completely shut off, allowing the brain to learn and usefully recall salient life events without being crippled by the emotional baggage that those painful experiences originally carried.
During Non-REM sleep, the body repairs and regenerates tissues, builds bone and muscle, and appears to strengthen the immune system. As you get older, you get less Non-REM sleep. People under age 30 have about two hours of restorative sleep every night, while those over 65 might get only 30 minutes.
Melatonin cycles change as we age. Teenagers actually have later cycles, which means they don’t get tired until 11 or midnight, unlike most adults who tend to get tired earlier. This is why calling teenagers “lazy” for sleeping in late may not be accurate; they’re simply adhering to their natural melatonin levels.
Research shows 20% learning advantages in a test comparing participants who napped and who stayed awake throughout the day. The stage 2 NREM sleep, and specifically the short powerful burst of electrical activity called sleep spindles, help replenish and restore the capacity of the hippocampus.
Tips for a better sleep:
Stick to a sleep schedule. Go to bed and wake up at the same time each day.
Try to exercise at least thirty minutes on most days and not later than two to three hours before your bedtime.
Avoid caffeine and nicotine. Caffeine’s effects can take as long as eight hours to wear off fully. Nicotine causes smokers to sleep only very lightly.
Avoid alcoholic drinks before bed. Having a nightcap or alcoholic beverage before sleep may help you relax but may rob you of your REM sleep.
Avoid large meals and beverages late at night. A large meal can cause indigestion, which interferes with sleep.
Want to take your learning to the next level? Visit our sign-up page and join a Vialchmey Personal Development Cohort now.
