Circadian Rhythm

Circadian Rhythm

• 00:00 Midnight
• 02:00 Deepest sleep
• 04:30 Lowest body temperature
• 06:45 Sharpest rise in blood pressure
• 07:30 Melatonin secretion stops
• 08:30 Bowel movement likely
• 09:00 Highest testosterone secretion
• 10:00 High alertness
• 14:30 Best coordination
• 15:30 Fastest reaction time
• 17:00 Greatest cardiovascular efficiency and muscle strength
• 18:30 Highest blood pressure
• 19:00 Highest body temperature
• 21:00 Melatonin secretion starts
• 22:30 Bowel movements suppressed

What is Circadian Rhythm

In advanced photosensitive organisms, the biological clock is a functional system composed of photosensitive neurons, the endocrine system, and gene temporal oscillation regulation, enabling organisms to form day-night rhythms from the microscopic level of gene expression and cellular metabolism to the macroscopic level of biological behavior.

Circadian rhythms have two major elements:

• Entrainment
• Period

Among them, the suprachiasmatic nucleus in the brain is the master clock, responsible for integrating external light signals and transmitting information to peripheral clocks in the body. This master clock calibrates once a day, based on light. Calibration occurs once every day-night cycle, with a 24-hour period.

Besides the optic nerve, other cells in the body don't have light-sensing capabilities. Although they're always active, they work "in the dark" because they can't "see," so things can get out of sync. The master clock plays the role of chief conductor, able to receive signals from the optic nerve and then transmit signals from central to peripheral levels, synchronizing time. The endocrine system, through hormone secretion, plays the role of transmitting signals sent by the central clock.

At the molecular level, how is the biological clock system constructed? The answer to this question was revealed by many scientists, including the three Nobel Prize winners.

For answers to this question, you can check [Zhihu column Wu Sihan's answer](see Wu Sihan's answer on Zhihu column)

Nobel Prize in Physiology or Medicine

To be supplemented...

Recommended Lifestyle Based on Circadian Rhythm

7:00 - 7:30 Wake up, best time

Open the curtains and let daylight tell your body to wake up from sleep as soon as possible, adjusting the biological clock to prepare for work.

Drink a glass of warm water - many people have this good habit. It replenishes water consumed during a night's sleep while moisturizing the body and stimulating vitality. Water is necessary for thousands of chemical reactions in the body. Drinking water helps every dehydrated cell regain vitality. Do body stretches, not too vigorous.

7:20 - 8:30 Eat breakfast, elimination

Breakfast must be eaten, everyone understands. Liquid foods are better. Not eating breakfast causes significant damage to the body. A morning of focused work and study requires normal energy and blood sugar. If conditions allow, try to have high quality.

9:00 - 10:00 Do difficult work

Best time for learning and work. At this time, the mind is clearest and thoughts are most lucid. For office workers, it's good for planning proposals and writing articles. In school, it's for difficult subjects like languages, math, and foreign languages. Never use this precious time to watch movies or browse JD and Taobao.

10:20 Let your eyes rest

Look out the window, rub your eye sockets - your eyes are tired and need a rest.

14:00–16:00 Fastest reaction speed

Very suitable for creative work. Good for meetings, brainstorming, thinking about work innovations. Even small improvements accumulate to great achievements over time. Need deliberate practice.

17:00 Strongest cardiopulmonary function - suitable for exercise

Gentle brisk walking, slow jogging, swimming, basketball, etc., according to personal needs and preferences. Can both consume dinner calories and easily lose weight.

20:00 Read or watch TV

If work is too hard, watch TV or read books and magazines, which can actually make you more relaxed and casual.

If you want to learn more, read professional books, which are very important for personal accumulation and creation.

21:00 Melatonin begins secretion, 22:30 Bowel movements suppressed

To ensure adequate sleep and all body systems, it's time to sleep.

Generally, people feel 10:30 is too early to sleep, but it's best not to exceed 11 PM. To ensure efficient learning and work, we must have a healthy sleep schedule, otherwise much time will be wasted because wrong sleep schedules will leave you with poor energy all day and low work efficiency.

Detoxification Can Rest Now

Similar to circadian rhythm is the popular claim that various organs have fixed detoxification times, such as the liver detoxing from 1 AM to 3 AM, as shown in the image below.

This originated from a book published in 2002 by Taiwanese Lin Guangchang called "Detoxification for Health." He was a technical secondary school student in electrical engineering who later "studied" for numerous "degrees."

• After military service, Lin Guangchang chose "Honolulu University" in the US to study business administration through distance learning. Upon investigation, this school was not registered with the Ministry of Education, and Xinhua Net classified it as an "old foreign diploma mill" (referring to miscellaneous schools that help people get graduation certificates). According to Lin's own introduction, he was about 25 years old at the time. From the courses he took, he obviously hadn't prepared to enter medicine.
• His medical studies occurred in 1998. He studied at the affiliated hospital of Liaoning University of Traditional Chinese Medicine and did clinical internships at this school's affiliated hospital in 2002. Regarding the qualifications from Liaoning University of Traditional Chinese Medicine's affiliated hospital, Ivan, director of the hospital's foreign affairs department, told our reporter in an interview that Lin Guangchang only obtained clinical research certification there, which doesn't represent academic qualifications and is the same nature as internship certificates obtained by university students after graduation.
• In 2001, Lin Guangchang extended his medical studies to the US, beginning studies at "American Global University," receiving a doctoral degree from this school in 2003. "To apply to enter the American Global University Oriental Medicine Research Institute doctoral program, there are two basic conditions: graduation from medical school or sufficient medical credits, current physician (if no longer practicing, need to provide proof). My studies at the mainland medical school gave me sufficient medical credits." Lin Guangchang used this to prove his medical foundation.

Regarding his so-called detoxification times, on the Science Squirrel Club website, Dr. Li Qingchen refuted each claim. I've excerpted some comments:

In daily life, we often hear people say that sleeping can be beautifying for girls, but do you know that our body is amazing and has its own detoxification function? Below, I'll list the body's detoxification timetable to see if you've also neglected your detoxification time, affecting your health—The claim that sleeping can beautify has been around for a long time, and many people believe it without thinking, probably related to past personal experience. For example, staying up late makes people tired and haggard, and for beauties, their looks will be greatly discounted at this time. So, reasoning in reverse that sleeping can beautify seems logical. However, establishing this causal relationship is too far-fetched. The impact of sleep on health is actually an extremely complex issue. We'll talk about it later. First, let's see what this detoxification time is like. Every night from 9:00 to 11:00 is the lymphatic detoxification process, when the immune system becomes active. You should calm down, listen to music, and try to keep yourself as quiet as possible. This way, the immune system will smoothly complete detoxification work, increasing your immunity. —Truth: The author probably hasn't even figured out what the lymphatic system is. Tissue fluid entering lymphatic vessels becomes lymph, and tissue fluid is liquid filtered from blood plasma through capillaries. Normal people generate 2-4 liters of lymph per day, roughly equivalent to total plasma volume. The lymphatic system is constantly circulating. All lymph is finally collected through lymphatic vessels throughout the body and enters the right lymphatic duct and thoracic duct, entering veins. The physiological significance of lymphatic return is to recover proteins, transport fats and other nutrients, regulate fluid balance, and provide defense and immune functions. Lymph passes through multiple lymph nodes during return. The lymphatic sinuses in lymph nodes have many macrophages with phagocytic function that can remove red blood cells, bacteria, and other particles. This process is constantly happening. The 9:00-11:00 time period is not special for the lymphatic system. From 11:00 PM to 1:00 AM, the liver starts detoxifying. You should be deeply asleep. If you don't sleep, your liver will be very tired and will definitely be damaged. —Truth: The liver is the body's largest gland, not only closely related to tissues and organs throughout the body in metabolism of sugar, protein, fat, hormones, and vitamins, but also has secretion, excretion, and biotransformation functions. The liver's detoxification function is a biotransformation process. Taking alcohol as an example, 90%-98% of alcohol is metabolized by the liver (the rest by kidneys and lungs). Metabolism rate is 100-200mg/h.kg. A 70kg person metabolizes 7-14g of alcohol per hour. The metabolic products of this process are toxic to the body. If you want to reduce liver damage, not drinking definitely helps. For the liver's detoxification function, it's actually an hourly worker - whenever you drink, it activates alcohol detoxification function. If you don't drink from 11:00 PM to 1:00 AM, there's no detoxification happening. From 1:00 to 3:00 AM is gallbladder detoxification time. You should continue sleeping deeply to facilitate liver-gallbladder detoxification. —Truth: Many people have a misconception about the gallbladder, thinking bile is produced there. Actually, bile is continuously secreted by liver cells. During non-digestive periods, after bile is generated, it flows out through the hepatic duct, with part entering the duodenum and part entering the gallbladder for concentration and storage. During digestion, the gallbladder contracts and bile enters the small intestine to participate in digestion. That is to say, the gallbladder releasing bile requires food stimulation. If the gallbladder only released bile from 1:00 to 3:00 AM, digestive function would really have problems. From midnight to 4:00 AM is the spinal hematopoiesis period. You must sleep deeply and never stay up late! —Truth: During the embryonic period, the yolk sac produces blood, then the liver and spleen, and bone marrow starts producing blood after 4 months and gradually strengthens. By the time the infant is born, it relies entirely on bone marrow for blood production. If adults have extramedullary hematopoiesis, it has no compensatory significance and represents hematopoietic dysfunction. Spinal hematopoiesis? Earthlings aren't like this. The author probably got confused, mixing up knowledge that adults have hematopoietic bone marrow in the vertebrae, ilium, ribs, sternum, skull, and proximal epiphysis of long bones. As for midnight to 4 AM? Nonsense. From 3:00 to 5:00 AM, the lungs start detoxifying. People who cough will have worse coughing at this time, but you shouldn't immediately take cough medicine to avoid inhibiting rapid elimination of waste from the lungs. —Truth: Cough medicine usually doesn't work, that's right. Coughing itself isn't a disease but a reaction to stimulation from some respiratory disease. It requires treating the cause. For example, if it's pneumonia caused by bacteria, antibiotics are needed. The main function of the lungs is breathing, inhaling oxygen and expelling carbon dioxide. As for detoxification... try deliberately inhaling a bunch of toxic waste gas and you'll know - it will immediately cause severe coughing, regardless of what time you inhale. From 5:00 to 7:00 AM is the large intestine detoxification time, the best time to use the toilet. If you don't have a bowel movement, it means you have something abnormal and really need to go to the hospital. Check what's wrong. —Truth: Whenever you need to defecate, go. If you have the urge at 4:30 every day but insist on waiting until 5:00, that's not a problem with bowel function but with the brain being kicked by a donkey. From 7:00 to 9:00 AM is when the small intestine starts absorbing nutrients in large quantities. You should eat breakfast before this. Otherwise, your nutrition for the whole day will be deficient. People being treated for diseases should eat by 6:30; people maintaining health can eat by 7:30. I advise friends who aren't used to eating breakfast to definitely develop the good habit of eating breakfast every day, even if it's delayed until after 9:00, you must eat. —Truth: The small intestine is indeed the main absorptive organ, including water, inorganic salts, sugar, fat, protein, and cholesterol. Does the small intestine stop absorbing when you eat dinner? Joke! As for breakfast time, this suggestion is originally the meal time for most people, it's correct but useless nonsense. There's no evidence that not eating during this time period has any harm, and those being treated for diseases or maintaining health don't need to eat at a specific time. This statement is purely sensational alarmism.

Dr. Li Qingchen debunked the so-called body detoxification timetable from a professional perspective. Lin Guangchang's final outcome was that his promoted detoxification therapy caused several cancer patients to refuse chemotherapy and ultimately die. He was investigated by Taiwan's judicial authorities and finally convicted of fraud, sentenced to two years and six months.

Talking About Sleep

After discussing so much about circadian rhythms, let's officially talk about sleep.

The Harm of Sleep Debt

Modern people, especially those living in big cities, face increasing life pressure and faster pace. Time is needed for socializing, learning, and entertainment, resulting in less and less time for sleep. Insufficient sleep time is becoming increasingly common, forming "sleep debt." Sleep debt is like owing money - once it accumulates, you become unable to repay it, and eventually your brain and body will be uncontrollable, leading to physical "bankruptcy."

Brain Hibernation

The American academic journal Sleep published interesting experimental results about sleep debt.

Doctors who worked night shifts and those who didn't were asked to perform an experiment. The specific method was to have them watch a display screen for 5 minutes, during which about 90 circles would appear. Each time a circle appeared, they pressed a button. The results were surprising. Radiology and endocrinology doctors with normal sleep could respond correctly to the graphics. However, doctors who had worked night shifts experienced three or four instances of no response to graphics for several seconds - they actually fell asleep.

The state presented by doctors who worked night shifts is called microsleep, which can be confirmed through their brain waves. Microsleep refers to a sleep state lasting 1 to 10 seconds; it's a defensive reaction to protect the brain.

I once experienced this condition while waiting at a red light while driving. Microsleep - thinking about driving in this state is truly very dangerous.

Harm of not sleeping:

• Not sleeping causes insulin secretion disorders, leading to elevated blood sugar and inducing diabetes
• Not sleeping causes leptin, which controls overeating, to stop secreting, causing obesity
• Not sleeping causes ghrelin, which increases appetite, to secrete, inducing obesity
• Not sleeping causes the sympathetic nervous system to remain tense for long periods, causing hypertension
• Not sleeping increases the incidence of mental diseases. Also causes alcohol dependence, drug dependence, etc.

Benefits of Repaying Sleep Debt

Sleep debt causes many harms, but if you can repay this "debt," performance levels will improve dramatically.

Professor Dement had Stanford University men's basketball players sleep 10 hours every night for 40 days, then investigated the impact on daytime activities. The first few days didn't show much change, but after 2 weeks, 3 weeks, 4 weeks, the 80-meter shuttle run time actually shortened by 0.7 seconds, and free throw accuracy also improved by 0.9. Players also felt "in good condition" and "games went smoothly."

After the 40-day experiment ended, players' sleep time returned to normal, no longer maintaining 10 hours of sleep, and their athletic performance returned to original levels. That is to say, improvements in attention, thinking ability, and reduction of mistakes were all related to sleep.

Sleep Process Science

Paying attention to diet and exercising to maintain health has become common knowledge among business people. Only sleep, as a good foundation, can improve the effects of diet and training.

The Sleep Process

Excellent people are busy and find it hard to ensure sleep time, so they need to maximize sleep quality. How can we scientifically improve sleep quality? First, let's understand the sleep process.

From falling asleep to waking, people don't remain in the same state throughout.

Sleep types include:

• REM (rapid eye movements) sleep - A state where the brain has awakened but the body is still deeply asleep
• Non-REM (non-rapid eye movements) sleep - A state where both brain and body are deeply asleep

During sleep, these two sleep states ==alternate repeatedly==.

Non-REM sleep and REM sleep alternate repeatedly

After falling asleep, non-REM sleep arrives immediately, especially the first 90 minutes of non-REM sleep, which is the deepest sleep of the entire sleep process. At this stage, "large-scale and slowly moving waveforms" appear, indicating the brain is in an inactive state, as shown below.

After 90 minutes of sleep, the first REM sleep appears. At this time, eyeballs move rapidly under the eyelids, hence rapid eye movement. In this condition, you have (more realistic) dreams. Although you remain unconscious during REM sleep, it's easy to wake up. From normal sleep patterns, before dawn, REM sleep and non-REM sleep repeat four or five times, and as dawn approaches, REM sleep duration lengthens. After daybreak, waking during light and long REM sleep is a natural state.

Therefore, the 90 minutes of deepest sleep appearing shortly after falling asleep is the key to achieving optimal sleep.

Brain waves at different sleep stages

The First 90 Minutes - The "Strongest Hormone" of Sleep

When growth hormone secretion is most vigorous is when the first non-REM sleep appears. As its name suggests, "growth hormone" relates to children's growth and plays an important role in promoting cell growth and normal metabolism in adults, helping with anti-aging.

Why Do We Spend 1/3 of Our Lives Sleeping?

Five Missions of Sleep

After a good night's sleep, what state are your brain and body in the next morning?

• Mind is clear, easy to come up with inspiration and ideas
• Attention is very focused, not easily interrupted, thinking precision is also improved
• Physical condition is excellent, so can concentrate on work

If the sleep process goes smoothly at night, performance the next day will definitely be good. From a long-term perspective, it also relates to brain, body, and mental health.

Let Brain and Body Rest

The autonomic nervous system's activity in the human body is not controlled by subjective will. It mainly maintains body temperature, heartbeat, breathing, digestion, and regulates hormone secretion and metabolism. The autonomic nervous system includes the sympathetic nervous system in active states and the parasympathetic nervous system in relaxed states, active 24 hours a day, alternately taking the dominant position.

During the day, the sympathetic nervous system is dominant, the brain is tense, and attention is more focused; during non-REM sleep or after meals, the parasympathetic nervous system takes over the dominant position.

Both nerves are very important, but business people's trouble is that the sympathetic nervous system dominates for too long, both body and brain feel tired. If the parasympathetic nervous system cannot smoothly take the dominant position at night, people will have difficulty falling asleep, sleep becomes shallow, and over time, bodily functions will become abnormal.

During early sleep, in the golden 90 minutes when the deepest non-REM sleep appears, letting the parasympathetic nervous system take over, letting the brain and body rest, is the first major mission optimal sleep should complete.

Organize Memory and Root It in the Brain

• During REM sleep, memories about events (what was done when and where) become rooted in the brain
• Non-REM sleep appearing during the golden 90 minutes can help eliminate bad memories
• Light non-REM sleep appearing early in sleep and before dawn allows us to physically solidify memories (non-conscious memories)

Recent reports also show that during the deepest non-REM sleep appearing shortly after falling asleep, information transfers from the hippocampus to the cerebral cortex, and memory is thus preserved. For memory, sleep is indispensable

Regulate Hormone Balance

The brain controls the balance of internal hormones, and during sleep, secretion of many techniques is active. Sleep and hormone balance have an inseparable relationship.

Improve Immunity and Stay Away from Disease

Immunity is related to hormones and thus also has a deep connection with sleep. One major function of sleep is rest, so from the perspective of improved immunity and rest, sleeping more to cure colds is reasonable.

Remove Waste from the Brain

When we're awake, nerve cells are also active, and waste accumulates in the brain. Although waste is also removed during waking hours, this is far from enough. So when sleeping at night, the brain performs its own "maintenance" work.

If waste in the brain cannot be effectively removed, it may become a trigger for Alzheimer's disease and other illnesses, and can damage the brain.

Golden 90-Minute Sleep Rule

Never ignore the first drowsiness. Obviously sleepy but insisting on not sleeping, afterward it's very difficult to enter deep sleep, and no matter how long you sleep, you won't have good sleep quality.

The first sleep cycle is "falling asleep-non-REM sleep-REM sleep," the second cycle is "REM sleep-non-REM sleep-REM sleep," and it repeats like this, with each cycle lasting about 90 minutes.

Usually after repeating 4-5 times, sleep gradually becomes lighter and enters REM sleep stage. If you wake up at this time, it couldn't be better.

If sleep time is 6-7 hours, this 90-120 minute sleep cycle can repeat four times.

But sleep quality still depends on the quality of the first cycle.

How to Ensure Golden 90-Minute Sleep?

Stick to sleeping at the same time and waking at the same time every day. Humans are affected by daily rhythms, so sleeping at night (11 PM) and waking during the day (7 AM) is most reasonable.

However, for most business people, this is very difficult to achieve. But according to the golden 90-minute rule, when feeling drowsy, sleep first, then wake during the first REM sleep and start completing remaining materials. The time when the first REM sleep appears varies by person, so when setting alarms, it's recommended to set the time for 90 (100/110) minutes later. This way, although total sleep duration is still insufficient, quality advantages are maximized.

Body Temperature and Brain Are Sleep Switches

Body Temperature Switch

In high-quality sleep, body temperature decreases. Core body temperature is characterized by being high during the day and low at night. But hand and foot temperature (surface body temperature) is the opposite - low during the day and high at night. Before falling asleep in healthy people, hands and feet start becoming warm, surface body temperature rises, heat dissipates through the body surface causing core temperature to decrease. At this time, the difference between surface temperature and core temperature narrows to within 2 degrees.

The key to falling asleep smoothly is to narrow the difference between core temperature and surface temperature. This is the first switch to achieving golden 90-minute sleep.

Brain Switch

Business people's brains remain excited and tense for long periods. This is because work pressure and physical fatigue force the brain to remain active, and when the brain is excited, body temperature is hard to lower.

Correctly turning off the "brain switch" can effectively prevent disorder during early sleep.

Stanford High-Efficiency Sleep Method

Use Body Temperature and Brain to Create Optimal Sleep

Humans are mammalian homeotherms, so body temperature has homeostasis and remains basically constant. But due to circadian rhythm influence, the biological clock regulates subtle daily temperature changes. For people with normal body temperature of 36 degrees, daily temperature variation amplitude is about 0.7 degrees. Body temperature rises during active daytime states and decreases during nighttime rest.

This shows that body temperature indeed has an inseparable connection with personal state. Body temperature decrease ensures smooth entry into sleep.

When we're awake, core temperature is about 2 degrees higher than surface temperature, but during sleep, core temperature decreases by about 0.3 degrees, and the difference between the two narrows to below 2 degrees. The research conclusion that people fall asleep more easily when the difference between surface temperature and core temperature narrows was published in Nature magazine in 1999

• When awake, body temperature rises, personal performance state also improves (switch turned on)
• Surface temperature rises (on), heat dissipation causes core temperature to decrease (off), allowing quick sleep
• During the golden 90-minute stage, if body temperature can smoothly decrease (off), sleep quality improves
• As morning arrives, body temperature starts rising (on), people gradually wake

Three Body Temperature Switches to Improve Sleep Quality

1. Bathe 90 minutes before sleeping

   Temporarily raising core temperature is very important because core temperature has the characteristic of decreasing as much as it increases.

   Therefore, consciously raising core temperature through bathing causes core temperature to decrease more significantly when falling asleep, which helps sleep.

2. Foot baths have amazing heat dissipation capacity

   The main body releasing heat is not our torso. What really dominates heat release are hands and feet with large surface areas and developed capillaries.

   Therefore, foot baths can improve foot blood circulation, promote heat release, achieving the same effect as bathing.

3. Room temperature adjustment to strengthen body temperature effects

   When room temperature is too high, body sweating exceeds standards, causing excessive heat release, leading to excessive body temperature decrease, resulting in colds.

   If room temperature is too low, blood circulation becomes poor, heat also cannot be released, making it difficult to fall asleep.

   Of course, the temperature each person can adapt to varies greatly, and there's no way to specify a specific temperature. But continuously running air conditioning while sleeping makes body temperature decrease easily, leading to colds.

But even if body temperature changes according to the ideal state, there may still be situations where you cannot fall asleep smoothly.

Such as: encountering worries, working right up until bedtime, or playing games, using phones keeping the brain excited, all make it hard to fall asleep and don't ensure sleep quality.

Maintaining a normal state is the trick to switching the brain to sleep mode. It's best to think about nothing before sleep; in other words, let the brain empty.

Three Brain Switches to Improve Sleep Quality

1. Monotony principle

   In a monotonous state, the brain is more easily emptied, no longer thinking about any problems, while feeling bored and easily drowsy. Try to consciously create this monotonous state. Pre-sleep entertainment should preferably be mindless, relaxing activities.

   Boring things aren't very popular but are good sleep companions.

2. The correct method of counting sheep

   Count sheep in English, because it sounds similar to sleep. The pronunciation of sheep is simple. Hold your breath while saying it, which has the effect of inducing sleep.

Sleep Forbidden Zone

Under normal circumstances, if a person doesn't sleep, sleep pressure in the body rises. The more you don't sleep, the more you want to sleep. Sleep pressure should be greatest before bedtime, and you should be most tired before falling asleep.

But through the "A 90 minute day" experiment, it was found that about two hours before normal sleep time is actually the most difficult time to fall asleep. Specifically, subjects had difficulty falling asleep during the 6 periods (days) before their normal sleep time. If converted to actual sleep, it's equivalent to people who sleep at midnight having the most difficulty falling asleep during the two hours starting at 10 PM. Like this, there's a ==forbidden zone== before falling asleep where the brain will resist sleep.

So if you must wake up early tomorrow, what to do?

Due to the sleep forbidden zone, it's best not to force yourself. Still fall asleep at the normal time and work hard to ensure sleep quality. If you still want to sleep an hour earlier, it's recommended to consciously raise your body temperature, such as bathing an hour earlier than usual, and doing simple exercises like stretching.

Most important is still the feeling of "really wanting to sleep." Body temperature, brain, techniques, and autonomic nervous system activities are interconnected. So the ideal state is to sleep when you want to sleep, especially going to sleep when feeling drowsy at night - this is the strongest sleep switch.

Solving snoring problems

During the day, consciously practice abdominal breathing through the nose. Based on this, calm the sympathetic nervous system through deep breathing every night while letting the parasympathetic nervous system take the dominant position. After getting used to this abdominal breathing, mouth breathing won't occur during sleep, thus solving snoring problems.

Ultimate Awakening Strategy

"Sleep" and "wakefulness" are originally a combination. Behavioral habits from morning awakening to nighttime sleep can create high-quality sleep, and high-quality sleep also helps with optimal daytime performance.

If you dawdle in getting up in the morning, you'll be in drowsiness all day. Plus negative impacts from wrong nap methods will cause nighttime sleep switches to fail to open normally.

==Once it takes longer to fall asleep, it becomes very difficult.== Even if you fall asleep, it's in a light sleep state, and you'll miss the golden 90 minutes, causing overall sleep quality to decline. The next day you still can't get up, thus falling into a vicious cycle.

Therefore, if you have sleep troubles, try starting from morning to change your waking behavior.

Awakening Switches

1. Light

   Human circadian rhythm is about 24.2 hours. The reason we can synchronize with Earth's "24-hour" rotation is because of light.

   Light changes create changes in "morning, noon, and evening." Without light, we wouldn't realize morning and night, and rhythms of body temperature, autonomic nerves, brain, and hormone activities would be disrupted.

   For such important light, you can get it just by opening windows, so ==definitely develop the habit of sunbathing in the morning==, even for just a few minutes. Even on rainy, cloudy days without sunlight, light that can affect body rhythms and wakefulness reaches the brain.

2. Body temperature

   Body temperature is mainly affected by circadian rhythm. Body temperature decreases during sleep and rises when awake.

   Raising body temperature when awake, opening the awakening switch, is key to ensuring good wakefulness.

Awakening Strategies

1. Set two alarms

   Although there are individual differences, human sleep cycles are basically about 90 minutes per cycle. As morning approaches, non-REM sleep decreases and REM sleep increases.

   Morning REM sleep duration lengthens, and the time from non-REM sleep to REM sleep is about 20 minutes. This method targets this timing strategy. It's easy to wake during REM sleep; even very small sounds can easily wake people.

   Specifically, set two alarms: one for when you need to wake up, one 20 minutes earlier (and this alarm has very quiet sound), ensuring you wake during REM sleep.

2. Stay away from sleep-inducing substances

   After waking, body temperature naturally rises. If you start moving immediately at this time, you can promote smooth opening of the body temperature switch.

   Melatonin has the effect of adjusting body rhythm and promoting sleep, so its secretion must be suppressed when awake. Sunlight plays an important role in suppressing melatonin secretion.

3. Going barefoot helps maintain wakefulness

   Auditory and visual stimulation activates the ascending reticular formation. Effectively using this characteristic, stimulate senses in the morning to wake refreshingly.

   Try going barefoot. First, directly touching the floor brings stimulation to the skin, activating the ascending reticular formation. Second, barefoot causes surface body temperature to decrease. Due to circadian rhythm influence, the naturally rising core temperature and surface temperature difference can further widen.

4. Washing hands awakens

   To wake the brain, washing hands with cold water is recommended, also to make hands contact water so the difference between core temperature and surface temperature becomes larger.

5. Chewing helps strengthen sleep and memory

   Breakfast plays an important role in raising body temperature, adjusting daily rhythm, and starting activities - "energy replenishment." Moreover, eating breakfast with ==thorough chewing== helps make our daily state measured and controlled.

   People who don't chew thoroughly when eating have no difference between "awake" and "sleep" states, memory also declines, and they also gain weight - in short, no benefits.

6. Try to avoid sweating profusely

   Jogging, exercising, etc. are all beneficial for making the sympathetic nervous system dominant. However, if exercise amount is too large, body temperature rises too much, causing sweating and heat release phenomena. Body temperature will decrease to levels lower than original body temperature, which is a signal of drowsiness.

7. Coffee brings far more than caffeine

   For caffeine concentration in blood to reach half requires about 4 hours. People who usually drink lots of coffee should switch to decaf from evening. From the perspective of improving daytime efficiency and opening awakening switches, coffee can indeed speed up basic metabolism, switching the body to awakening mode.

8. Change the time for "doing important work"

   Work requiring brainpower, important work should all be concentrated in the morning as much as possible. After lunch, gradually transition to simple work mode, letting the brain gradually relax, which also benefits nighttime sleep.

9. Not eating dinner also affects sleep quality

   Awakening substance - orexin is released by cells in the hypothalamus part of the brain. Not eating promotes orexin secretion, while eating causes its level to fall, and wakefulness degree also decreases. For "sleep" and "health," not eating dinner has all harms and no benefits.

Specific Implementation Measures for High-Efficiency Sleep Method

1. Golden 90-minute rule
   • Ensure quality of first 90 minutes of non-REM sleep
   • Use body temperature and brain switches to fall asleep quickly
     • Narrow core temperature and surface temperature difference to within 2 degrees
       • Shower/foot bath one and a half hours before sleep
       • Adjust room temperature (~17 degrees)
     • Brain monotony principle
       • Don't think about complex problems
       • Record things you're worried about
       • Prepare everything needed for the next day
2. Use 90 minutes as one sleep cycle
   • Measure sleep by 90-minute sleep cycles, not how many hours slept
   • Choose sleep time yourself; sleep time depends on wake time, count backward from wake time
   • Consider sleep over a longer period; obtaining 30-35 cycles per week is ideal
   • Try to avoid three consecutive nights of insufficient sleep
   • At least 4 nights per week should obtain ideal sleep time
3. Early rising awakening strategy
   • Set two alarms, one on time, one 20 minutes early (quiet sound)
   • First thing after getting up: open curtains, feel sunlight
   • Lower surface body temperature, widen core and surface temperature difference
   • Can do gentle exercise to raise core temperature, also to widen core and surface temperature difference
   • Chew breakfast thoroughly; chewing can strengthen sleep and memory
4. Daytime routine adjustments
   • Do mentally demanding, difficult work in the morning
   • Midday nap - 20 minutes is best
   • Evening 17:00 can insert controlled recovery sleep

Alright, I've expanded on both principles and specific measures. Now it's time to witness the sleep miracle!!!