"Throughout one's life, one-third of the time is spent asleep. Sleep is an indispensable part of life maintenance. It sustains normal brain function, promotes physical and mental restoration, safeguards the brain, enhances memory, boosts immunity, regulates emotions, and ensures overall well-being. Good sleep quality is crucial for the growth and development of children." Recently, at the "2024 World Sleep Day Popular Science Lecture and National Free Clinic Event" hosted by the Sleep Medicine Professional Committee of the Chinese Medical Association, Academician Lu Lin of the Chinese Academy of Sciences remarked.
Academician Lu Lin is giving a presentation (Image provided by the Chinese Medical Association)
March 21 marks the 21st World Sleep Day. Statistics show that the prevalence of sleep disorders among people aged 60 and above in China is 35.9%, while among adolescents, it's 26%. Inadequate sleep has numerous negative effects on health, with insomnia disorders alone costing the global healthcare system up to $100 billion annually.
In recent years, the prevalence of sleep disorders in China has been increasing and gradually trending toward a younger demographic. So, how can we rescue those elusive hours of sleep?
The Wonders of Brain Function during Sleep
The two most common types of sleep disorders are insomnia disorders and sleep-breathing disorders. With advancements in science and technology, there's been increasing public interest in sleep-related research. Factors such as light exposure, ambient temperature, exercise, and melatonin have all been found to have a certain relationship with sleep.
"When people sleep in well-lit rooms, their heart rate significantly increases, and even if asleep, the autonomic nervous system remains active. Moreover, strong light exposure at night can disrupt the body's ability to rest effectively," stated Lu Lin. Approximately 90% of people use electronic devices before bedtime, and the short-wave light emitted by these devices can disrupt normal circadian rhythms, leading to sleep issues.
A study comparing the effects of reading e-books versus printed books before bedtime found that participants who read e-books had more difficulty falling asleep, decreased nighttime sleepiness, and disrupted biological clocks compared to those who read printed books.
Furthermore, researchers at the University of Bern in Switzerland found that ambient temperature can also alter sleep architecture and play a crucial role in melatonin secretion.
"Suitable sleep temperature promotes a more structured and higher-quality sleep experience," noted Lu Lin. Regular aerobic exercise significantly lowers the concentration of catecholamines in the body, enhances parasympathetic nervous system activity during nocturnal quiet periods, thereby reducing nighttime awakenings. Exercise also promotes melatonin secretion, affects melatonin degradation, alters plasma melatonin concentrations, thereby regulating sleep rhythms and improving sleep quality.
Closely Associated with Many Diseases
"The brain needs sleep for necessary repairs and cleansing after a busy day, helping the brain 'clear redundancies' to ensure normal metabolism and function the next day," Lu Lin explained. Sleep disorders can lead to increased mental stress, resulting in various mental illnesses such as anxiety disorders, depression disorders, schizophrenia, etc.; they can cause various physical illnesses such as hypertension, myocardial infarction, hyperlipidemia, obesity, immune dysfunction, and even premature birth. They can also cause cognitive impairment, leading to decreased concentration and memory loss.
However, sleep remains a mysterious and miraculous function of the brain. Research has shown that sleep and immunity interact, inflammatory responses activate the immune system, which can disrupt normal sleep, while good sleep can reduce the risk of infection, improve infection outcomes, and reduce vaccine reaction.
"Both too much or too little sleep and other causes of sleep disorders may increase the risk of diabetes, possibly due to the regulation of insulin's rhythmic secretion by the circadian rhythm," said Lu Lin. Diabetes patients may experience neuropathic pain due to peripheral neuropathy or other diabetes-related sleep disorders such as nocturia, reducing sleep quality. Sleep disorders and diabetes can both induce cognitive impairment, further exacerbating cognitive impairment.
Studies have shown that sleep disorders have a bidirectional relationship with Alzheimer's disease. Sleep disorders may be closely related to the pathogenesis of Alzheimer's disease, while Alzheimer's disease itself may also affect sleep quality.
A meta-analysis by Lu Lin's team showed that compared with normal individuals, people with sleep disorders have a significantly increased risk of all types of dementia. Insomnia is prone to increase the incidence of Alzheimer's disease, while sleep-breathing disorders may more easily lead to all types of dementia.
A study involving 4,040,044 people also found that when sleep duration is longer, the incidence of hypertension, atrial fibrillation, pulmonary embolism, and chronic ischemic heart disease is lower. "This suggests that short sleep duration (≤6 hours) may increase the risk of hypertension, atrial fibrillation, pulmonary embolism, and chronic ischemic heart disease," said Lu Lin.
Moreover, researchers from the University of California studied 3 million pregnant women over a period of 6 years and found that sleep disorders during pregnancy significantly increased the risk of preterm birth, with insomnia disorder increasing the risk by 30% and sleep-breathing disorders increasing the risk by 50%.
In response, the journal Nature published a commentary calling for attention to the sleep issues of pregnant women, recommending the development of more sleep interventions suitable for special populations such as pregnant women.
The Path to Good Sleep
So, what measures can improve sleep quality?
In response, Lu Lin emphasized self-training to achieve regular sleep patterns. "No matter how long you slept the previous night, try to wake up at a fixed time as much as possible, avoiding lying in bed or sleeping in excessively. There shouldn't be too much difference on weekends; just sleep until you can recover your energy the next day, without overly stressing about the length of sleep."
At the same time, avoid excessive stimulation before bedtime. For example, stop active mental activities at least 1 hour before bedtime. Additionally, the bedroom should be dimly lit at night, and one should only go to bed when feeling significantly drowsy, avoiding watching TV or using phones in bed. Typically, 18.3 degrees Celsius is an ideal temperature for most people to easily fall asleep.
There's also a certain art to sleep accessories. For instance, the mattress should be relatively firm, not overly soft or sagging, and combined with personal preferences, choose a comfortable pillow with a height of about 10 centimeters. In terms of sleeping posture, sleeping on the right side is preferable, and if there's pain in the limbs, avoid pressure on the painful areas while lying down. "When facing difficulty falling asleep, it's important to encourage oneself with positive language instead of reinforcing thoughts like 'I must fall asleep quickly' or 'I won't sleep again tonight', as this can actually hinder the body from entering sleep mode," suggests Lu Lin. For individuals with sleep disorders, Lu Lin recommends diverting attention through healthy activities such as listening to music or drawing to avoid excessive focus on sleep and emotional issues.
Moreover, maintaining a scientific diet can also contribute to better sleep. Firstly, it's essential to have three regular meals a day, especially breakfast, as this can regulate the body's functioning mechanisms and positively impact sleep. Secondly, it's best to avoid eating right before bedtime, with dinner ideally concluding three hours prior to sleep. Additionally, it's advised to refrain from consuming stimulating substances like alcohol, coffee, or strong tea before bedtime.
Addressing the common practice of self-administering melatonin and similar substances to improve sleep, Lu Lin emphasizes that these drugs are not universally effective for all insomnia cases, particularly when insomnia is caused by mental disorders, physical illnesses, or substances such as alcohol and coffee. Furthermore, long-term use of melatonin can disrupt the body's natural melatonin secretion levels, further exacerbating sleep dysfunction.
Lastly, Lu Lin underscores that individuals experiencing sleep disturbances should seek timely medical attention if self-regulation proves ineffective. When necessary, resolving sleep problems may require medication and psychological counseling under the guidance of a healthcare professional.
