Today, it's World Sleep Day, and the theme is "Healthy Sleep for All". "Turn the Zhu Pavilion, low Qihu, shine sleeplessly" (Song Su Shi's "Water Tune Song Tou, When is the Bright Moon"), insomnia has plagued human beings since ancient times, and human beings have been trying to solve the puzzle about sleep.
Did you know that while almost all living organisms need sleep, there are significant differences in sleep patterns between different species, and even between individuals of the same species. Compared to humans, rodents have a shorter overall sleep duration, frequent sleep phase switching, and follow a polyphasic sleep pattern.
What is polyphasic sleep?
Polyphasic sleep is the idea of dividing your sleep into more than 2 parts of your day, rather than just sleeping at night (the most common sleep pattern in modern society).
Our earliest understanding of polyphasic sleep began with animals. Polyphasic sleep is common in the animal kingdom, with more than 86% of mammals exhibiting a typical polyphasic sleep rhythm, which is thought to be the sleep state of mammalian ancestors.
Think about your cats and dogs
Isn't it also a while to sleep and wake up for a while?
In the human world, usually adults sleep only once a day, the time is 6~8 hours, this sleep pattern is called monophasic sleep, and a long sleep of 6~7 hours in a day, plus a nap of about 0.5 hours, is called bipolar sleep.
Polyphasic sleep is to split the single sleep that humans are accustomed to into multiple sleep cycles (more than 2) to reduce the overall sleep time, and it also has a resounding name abroad - "da Vinci sleep".
According to legend, in order to save time for artistic creation, Leonardo da Vinci slept every 4 hours, sleeping for 15~20 minutes each time, so that he only slept for about 2 hours a day, which not only saved time, but also was energetic, which is the "4-hour sleep method" mentioned by Zhang Chaoyang.
Source: Video screenshot
On this basis, we have derived a series of polyphasic sleep patterns.
For example, the essence of the "Everyman Sleep Plan" is to divide sleep into one main sleep stage and three short small sleep fragments, sleep for 5~6 hours at night, and take a nap in any 3 stages during the day, each 30 minutes of sleep.
The "Ubrman Sleep Plan" divides the day into 6 equal parts, sleeping 6 times a day for 30 minutes each time, which adds up to 30x6=180 minutes, for a total of 3 hours. This type of sleep plan claims to compensate for sleep deprivation by increasing REM sleep (REM sleep period).
In addition to monophasic sleep, there are many different sleep modes (dark for sleep)| typewhiter.com
Although some humans claim that they follow sleep patterns such as "Da Vinci Sleep Method" and "Everyman Sleep", this is only a difference between individuals, and there is little evidence that polyphasic sleep was once a common practice for all human beings.
However, biphasic sleep has been common throughout history.
Roger Ekirch, a professor of history at Virginia Tech, argues in his book "At Day's Close: Night in Times Past" that waking up in the middle of the night was common, if not customary, in pre-industrial Western cultures.
At that time, when schedules were dominated by the sun rather than clocks and electric lights, people were likely to climb into bed earlier, and people were likely to rest longer than the short, sustained eight-hour sleep, perhaps consisting of two shorter periods of sleep, interspersed with a waking period.
During this waking hour, people would do household chores, such as sewing and mending by the light of the fire, combing wool, and even chopping wood and doing farm work in the moonlight. In the middle of the night, people return to bed and sleep until dawn.
Polyphasic sleep, is it worth it for humans?
Since most animals in nature have polyphasic sleep, and historical data shows that humans do have biphasic sleep practices, is it possible for modern humans to practice polyphasic sleep today?
There are different views on this.
Some people think that the polyphasic sleep pattern is the sleep mode of human beings, but with the advent of the industrial revolution and the emergence of artificial light sources, human beings began to override the natural night and reduce the time of sleep, thus forming a monophasic sleep pattern.
Daniel Buysse, a professor of psychiatry, medicine, clinical and translational medicine at the University of Pittsburgh, said that because we are always compressing our sleep time, the two processes of sleep (intrinsic rhythm and circadian rhythm) are "mixed together" and if we are given more time, the two processes may separate, allowing us to wake up naturally according to our inner sleep rhythm. In fact, the waking period between several periods of slumber may also play a survival function.
It is also believed that human babies also have obvious polyphasic sleep rhythms, and it is only when they grow up and enter society that they have to be forced into monophasic sleep because of a variety of factors. Researchers have pointed out that there is little reason to think that the human sleep/wake system will evolve in a completely different way. Psychologist Claudio Stampi believes that in cases of sleep deprivation, polyphasic sleep can be effective in improving sustained exercise performance.
However, modern medicine does not recommend polyphasic sleep.
Modern medical research believes that people's sleep throughout the night is generally divided into light sleep (N1, N2 stage), deep sleep (N3 stage), rapid eye movement sleep period (REM period) several parts, these parts constitute the sleep cycle, each sleep cycle is marked by the end of the REM period, a cycle is about 1.5 hours, a whole night has about 4~6 sleep cycles.
Comparison of artificial staging and model staging by sleep experts Source: References
Normal sleep is a process of periodic decline like a wave, and people sleep deeper and deeper the more they sleep. Some people "wake up easily" and fall asleep soon after waking up, but they sleep enough that according to the polyphasic sleep theory, as long as they have a REM period between two or more awakenings, there is no harm to their body.
But in fact, as long as the number of wake-ups in the middle of sleep reaches 2~3 times, it will bring obvious distress to people. At least judging from the cyclical changes in sleep EEG, there is no possibility of breaking up the night's sleep into six 15-minute REM periods.
Doctors suggest that if you can't get enough sleep at night, regular short naps can make up for sleep debt and restore energy to a certain extent, but this is only a temporary replacement when you have to do so, as long sleep deprivation or the implementation of the "Everyman Sleep Plan" or "Da Vinci Sleep Method" regardless of personal circumstances will lead to a series of changes in the human body.
One study found that people in their 30s and 40s who were constantly awake from sleep at night had a more than 2 times higher risk of developing cognitive problems after 10 years
For the first time, research on the "causes of cancer caused by staying up late" has confirmed experimentally that black and white reversal is a human carcinogen
Perhaps there is no specific sleep pattern in humans, and the above is just a difference between individuals. Because sleep is influenced by the natural and social environment, sleep patterns can vary widely between individuals, depending on the region and season, Beuys said. "In general, I don't think there's a certain human sleep pattern," "Adaptability is the main characteristic." ”
There are many mysteries of sleep that need to be uncovered
In recent years, thanks to the innovation and advancement of research methods, we have revealed the role of specific types of neurons in different brain regions in the brain in sleep-wake regulation.
The brain is not "turned off" during sleep, but "switched to work mode": many brain regions are still in a state of excitement during sleep, and even the maintenance of sleep itself depends on the normal operation of sleep-related circuits.
However, there are still many mysteries about sleep that remain unsolved. For example, why do we need sleep, what is the main function of sleep, what is the function of dreams?
On the other hand, sleep disorders have become a problem all over the world, and more and more people are suffering from sleep disorders. On March 18, 2024, the Chinese Sleep Research Association released the "2024 White Paper on Sleep of Chinese Residents", which showed that the overall sleep quality of mainland residents is poor, and the main sleep problems are easy to wake up early and difficult to fall asleep, and the sleep duration at night is generally short, with an average sleep duration of 6.75 hours. Sleeping until dawn is difficult for most people to achieve.
Hopefully, in the future, we will be able to reveal more about the mysteries of sleep, so that everyone can enjoy adequate and effective sleep.
Bibliography:
Polyphasic Sleep Wiki (polysleep.org)
link.springer.com/chapter/10.1007/978-1-4757-2210-9_1
弗吉尼亚理工大学历史教授罗杰•埃克里奇（Roger Ekirch）《黑夜史：一部西方人的黑夜生活史》（At Day's Close: Night in Times Past）
onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2869.2007.00567.x
Leonardo da Vinci's Sleep Method——CPPCC Network (rmzxb.com.cn)
HU Kailei, CHEN Jingxia, ZHANG Pengwei, XUE Wen, XIE Jia.Multimodal physiological time-frequency feature extraction network for accurate sleep staging[J].Journal of Biomedical Engineering,2024,41(01):26-33.)
Brown RE, Basheer R, McKenna JT, Strecker RE, McCarley RW. Control of sleep and wakefulness. Physiol Rev. 2012 Jul; 92(3):1087-187.
2024 White Paper on Sleep for Chinese Residents
Author: Wang Juan
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Editor-in-charge: Dong Xiaoxian
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