3.8 Sleep · ThinkerQAQ

This is a historical learning note and may contain outdated or incomplete understanding.

1. What Is Sleep?

A natural, recurring physiological state. During a certain period each day, conscious and active behaviors disappear and responses to external environmental stimuli become weaker.

2. Why Do We Need Sleep?

Restore physical energy: growth hormone secretion is strong at night.
Restore brain function: makes it easier to receive new information (hippocampus) + consolidates memory (fixes it into neural structures) + clears waste (including a toxic protein associated with Alzheimer’s disease) + stimulates creativity (integrates newly learned elements with previously learned elements).
Regulate emotions: the amygdala is responsible for emotions, and the prefrontal cortex can regulate the amygdala. When sleep is insufficient, communication between the two weakens, leading to emotional instability. Sleep can smooth out daytime trauma, retaining the memory without retaining the emotion.
Physical health: sleep is the foundation and can strengthen the immune system; diet and exercise are also needed on top of it.

3. How Is Sleep Produced?

3.1. Biological Clock / Circadian Rhythm

Determines when to stay awake and when to feel sleepy. Everyone’s biological clock is different. Some people’s cycle may be 24 hours, while others may be 23 hours.

3.1.1. Melatonin

The circadian rhythm is controlled by the suprachiasmatic nucleus in the brain, which releases a hormone called melatonin. It makes us feel sleepy. After sunset, secretion begins around 9 p.m., peaks around 11 p.m.–12 a.m., and has almost disappeared by daylight.

3.1.2. Cortisol

Keeps us awake. It peaks around 10 a.m., while reaction speed reaches its best performance around 3 p.m.

3.2. Sleep Drive System / Sleep Pressure

From the moment you wake up and get out of bed, this system begins building the drive for deep sleep. The longer you stay awake and the more active you are, the stronger the drive for deep and sustained sleep becomes at night.

3.2.1. Adenosine

The more adenosine there is, the sleepier you feel. After sleep, adenosine is cleared from the brain.

4. How Sleep Proceeds

4.1. What Is a Sleep Cycle?

Studies of brain waves show that a full night’s sleep can be divided into four to five cycles. Each cycle lasts about one and a half to two hours (around 90 minutes), and each cycle is called a sleep cycle.

4.2. Composition of a Sleep Cycle

4.2.1. Non-Rapid Eye Movement Sleep (NREM)

Used to restore physical energy. It is divided into three stages: drowsiness, light sleep, and deep sleep. Breathing becomes shallower, slower, and more regular; heart rate slows; blood pressure decreases; muscles throughout the body relax; gastrointestinal motility increases; basal metabolic rate decreases; and there are no obvious eye movements.

4.2.2. Rapid Eye Movement Sleep (REM)

Used to restore brain function. About 90 minutes after falling asleep, the body enters rapid eye movement sleep, characterized by rapid eye movements. At this stage, sensory functions decline further and muscles become even more relaxed. Blood pressure is higher than during NREM sleep, breathing is slightly faster and irregular, and body temperature and heart rate also increase. If someone is awakened at this point, they will usually say they were dreaming. During REM sleep, although brain waves are very active, the body’s muscles are inhibited and therefore weak. The folk phenomenon of “sleep paralysis” refers to this.

5. Insomnia

5.1. What Is Insomnia?

Objective: difficulty falling asleep or maintaining sleep on at least three nights per week. Subjective: insomnia is a subjective judgment and must involve daytime functional impairment.

5.2. Duration of Insomnia

Less than one month is acute insomnia; more than one month is chronic insomnia.

5.3. Severity of Insomnia

5.3.1. Intensity

30 minutes to fall asleep. Sleep duration: 6–6.5 hours.

5.3.2. Frequency

How many times per week.

5.4. Why Does Insomnia Occur?

5.4.1. Predisposing Factors

Biological: naturally high arousal system. Psychological: anxiety + excessive thinking. Social factors.

5.4.2. Precipitating Factors

Sudden events. Biological. Psychological. Social.

5.4.3. Perpetuating Factors

Spending too much time in bed or increasing behaviors unrelated to sleep in the bedroom.

5.5. How to Treat Insomnia

Insomnia is an outcome. You need to find the cause of that outcome, namely a dysregulation of body and mind.

Physical: Psychological:

5.5.1. Cognitive Behavioral Therapy for Insomnia (CBT-I)

“Cognitive Behavioral Therapy Counseling Plans — Seven Major Psychological Problems”.

5.5.1.1. Correct Incorrect Beliefs About Insomnia

Sleep is for rest, and lying down is also a form of rest. Is sleep continuous? No. In ancient times, people would sleep for 1–4 hours, wake for 1–2 hours, and then sleep for another 1–4 hours. How long should you sleep? As long as it is enough. There is no need to insist on eight hours; 5.5 hours is core sleep. Accept insomnia and enjoy sleep. Use smart wearable devices to monitor cycles.

5.5.1.2. Stimulus Control Therapy (SCT)

A required therapy for difficulty falling asleep + difficulty maintaining sleep. It limits time spent lying in bed while awake and behaviors performed in the bedroom and bed that are unrelated to sleep, in order to strengthen the association between the bed, bedroom, bedtime, and rapid, stable sleep.

Go to bed only when sleepy.
Do not stay in the bedroom except for sleep and sexual activity.
If you remain awake for more than 15 minutes, leave the bedroom.
Return to the bedroom only when sleepy again.

5.5.1.3. Sleep Restriction Therapy (SRT)

An optional therapy for difficulty falling asleep + difficulty maintaining sleep. Use a sleep diary to record time and restrict time in bed to the average total sleep time.

Delay bedtime.
Fix the wake-up time.
If sleep improves, gradually move bedtime earlier.

5.5.1.4. Sleep Hygiene Education

Sleep until you feel restored the next day.
Get up at the same time every day.
Exercise regularly: avoid exercise within three hours before bedtime; exercise at least three times per week so the body develops a regular exercise habit. Each session should last at least 30 minutes, preferably 45–60 minutes. During exercise, heart rate should be no lower than 130 beats per minute to achieve a better energy-expenditure effect.
Make sure the bedroom is comfortable and free from interference from light (especially blue light) and sound.
Keep the bedroom at a suitable temperature.
Eat regularly and do not go to bed hungry: having a late snack around 9–10 p.m. and resting for 1–2 hours before sleep is considered better; foods containing tryptophan, calcium, and magnesium are good. About 1.5 hours before sleep, you can drink no more than 200 mL of a non-stimulating liquid such as milk or eat a small amount of fruit such as one medium banana.
Avoid beverages at night.
Reduce caffeine intake: avoid caffeine-containing substances after the afternoon or within 3–6 hours before sleep.
Avoid alcohol.
Quit smoking.
Do not bring problems into bed.
Do not try to force yourself to sleep.
Do not look at the time.
Avoid daytime naps: for insomnia, naps should not exceed half an hour, and try not to make up sleep within eight hours before nighttime sleep.

Sleep depends on two cooperating systems: the biological clock and the sleep-drive system. Uncovering the Mystery of Biological Rhythms — 2017 Nobel Prize

The 3P model of insomnia. The longer you stay awake, the more time you spend active, and the greater the intensity of activity, the more sleep debt you accumulate. The greater the sleep debt, the easier it is to enter deep sleep at night. Exercise.

5.5.2. Relaxation Training

There are three types of tension: psychological, physical, and sympathetic-nervous-system tension.

5.5.2.1. Worry Time

Set aside half an hour every evening.

Write down the things you are worried about.
Categorize those things.
Think about solutions for each category.

5.5.2.2. Cognitive Restructuring

Negative Emotion Log.

5.5.2.3. Stretching

5.5.2.4. Progressive Muscle Relaxation

Practice This for Anxiety! Practice This for Panic Attacks! Progressive Muscle Relaxation Exercise - Bilibili

5.5.2.5. Meditation Practice

Abdominal breathing. Body scan.

5.5.3. Light Therapy

Correct disrupted sleep rhythms.

Get sunlight exposure as soon as possible after getting up for 2–10 minutes. At night, reduce exposure to artificial light sources as much as possible; dim red light with low illumination is better.

5.5.4. Medication

Use appropriately under a doctor’s guidance. Short-term (no more than four weeks), low-dose, intermittent use.

5.5.4.1. Sedatives

Commonly called sleeping pills.

5.5.4.1.1. Benzodiazepines

Suitable when anxiety symptoms are also present. They have more side effects, higher dependence potential, and a long half-life. They interfere with deep sleep and REM sleep.

5.5.4.1.2. Non-Benzodiazepines

Act quickly, have fewer side effects, lower dependence potential, and a short half-life.

5.5.4.2. Other Medications With Sleep-Promoting Effects

5.5.4.2.1. Antihistamines

Most anti-allergy medications have drowsiness as a side effect, so these medications may also be used to treat insomnia.

5.5.4.2.2. Antidepressants

Antidepressants can cause drowsiness and are therefore also often used to treat insomnia, especially insomnia in people with psychological disorders.

Low doses do not interfere with deep sleep.

5.5.4.2.3. Antipsychotics

There is currently no relevant empirical research supporting that these medications can effectively treat insomnia, but because they can make people feel groggy, they may be mistakenly thought to treat insomnia.

5.5.4.2.4. Melatonin

A natural hormone secreted by the pineal gland in the human brain that controls the body’s circadian rhythm. Suitable for treating sleep disorders caused by circadian-rhythm disruption.

5.5.4.3. How to Reduce Medication

Gradually reduce the medication dose each week. Gradually reduce the number of medication days each week. Use medication only when it is truly needed. For occasional insomnia, replace medication with relaxation and mindfulness training.

5.5.5. Anesthesia-Based Sleep Treatment

5.5.5.1. Stellate Ganglion Block

5.5.5.1.1. What Is the Stellate Ganglion?

The stellate ganglion is located on both sides of the seventh cervical vertebra. It is called the stellate ganglion because its shape resembles a star.

5.5.5.1.2. What Is a Stellate Ganglion Block?

A needle is inserted into the loose connective tissue around the stellate ganglion to stimulate or disrupt sympathetic nerves supplying the head and face, neck, upper limbs, and upper chest. This can temporarily relax persistently tense sympathetic nerves and gradually restore the balance between activation and relaxation in the autonomic nervous system.

Advantage: simple procedure.
Disadvantage: side effects may occur.

Local anesthetic enters the vertebral artery, causing central nervous system convulsions and respiratory or cardiac arrest.
Vascular injury causing a hematoma at the puncture site.
Injury to the recurrent laryngeal nerve near the tracheoesophageal groove, causing hoarseness.
Local anesthetic enters the subarachnoid space, causing total spinal anesthesia, respiratory depression, and cardiac arrest.
Allergy to the anesthetic drug.
Puncture of the pleural dome or lung apex causing pneumothorax.
Phrenic nerve block causing hiccups or reduced abdominal breathing.

5.5.5.1.3. Ultrasound-Guided Stellate Ganglion Block for Insomnia

Under real-time ultrasound guidance, local anesthetic is injected around the stellate ganglion and nearby tissues, helping relevant body systems maintain dynamic balance. Patients with primary sleep disorders often have sympathetic overactivity and imbalance between sympathetic and parasympathetic function. This can keep a person in a prolonged state of stress and hyperarousal, making it difficult to sleep when they should. Stellate ganglion block suppresses this excitation, regulates autonomic function, and restores balance.

5.5.6. Diet

5.5.6.1. Alcohol

It has no benefit for sleep and has disadvantages. Alcohol is a sedative. It can make you enter a sedated state more quickly, but that is not the same as a sleep state, which can be observed through brain waves. Alcohol fragments sleep and increases the number of awakenings.

5.5.6.2. Caffeine

Different people have different sensitivities to caffeine. Caffeine has a half-life of 5–6 hours, so it is best to drink it before noon. Also pay attention to foods other than coffee that contain caffeine, such as dark chocolate.

How does caffeine block sleepiness? It binds to adenosine receptors and prevents adenosine from taking effect. However, adenosine is not cleared and continues accumulating, so after the caffeine wears off, you feel even sleepier.

5.5.6.3. Nicotine

Smoking.

5.5.6.4. Tea

Theophylline - Wikipedia

Like coffee, it is also an adenosine-receptor antagonist and can block the effects of adenosine receptors.

Lunch and Dinner

At lunch, you can eat lower-calorie foods and foods containing tyrosine, such as nuts, soybeans, and some vegetables, to increase dopamine and adrenaline and stay awake.
In the evening, you can eat some starch and white meat rich in tryptophan, which can then be converted into serotonin and make people calmer and more likely to fall asleep.

5.5.7. Exercise

Daytime exercise stimulates the sympathetic nervous system; nighttime meditation stimulates the parasympathetic nervous system.