I read about a puzzling case of two Italians who had never had a real sleep. They would lie down and close their eyes, but the brainwave recordings showed that during their “sleep” there was no form of brainwave associated with normal sleep. During the “sleep” period, although they did not perceive their surroundings, they would sometimes get up and walk around, shout, tremble violently, and have a rapid heartbeat.
The rest of the time, they are awake, but prone to dream-like hallucinations. This may sound very contradictory, but scientists who study sleep are not surprised by this. They believe that there is no clear-cut line between sleep and wakefulness ……
Sleep inertia makes people suddenly “dumb”
It is widely believed that healthy people are in three states of alertness: wakefulness, rapid eye movement sleep and non-rapid eye movement sleep. The boundaries between these states are clear and can be confirmed by EEG monitoring of brain activity. However, many experiments and studies on sleep have found that the actual situation is much more complex.
Back in the 1980s, the American psychiatrist Dinges found that the different states of brain alertness could easily be mixed and crossed together. In the experiments he conducted, volunteers could do an average of 90 addition and subtraction arithmetic problems in 3 minutes while awake, with almost no errors; after 52 hours of sleep deprivation, their performance dropped, and they were able to do about 70 problems with a small number of errors; however, after 2 hours of sleep and being suddenly awakened, their performance dropped sharply, and they could not even do the simple questions.
”This phenomenon is known as ‘sleep inertia’, also known as ‘sleep inertia’, and refers to the temporary state of low alertness, confusion, behavioral disorders, and decreased cognitive and sensory abilities that occur immediately after a person is awakened. ” Dr. Wang Guoping, chief of the Department of Neurology at the Provincial Hospital, who is very knowledgeable about sleep, said, “People usually experience this state of confusion after being woken up by an alarm clock. At this time, the person is awake in terms of the ability to interact with the outside world, but in terms of brain function is still in sleep.”
According to Director Wang Guoping, who has many years of clinical experience, there are many other sleep disorders like this that arise from the blurring of the line between sleep and wakefulness. For example, REM sleep behavior disorder, when patients enter REM sleep, they will “act out” their dreams, dancing, mumbling, and even punching and kicking with their dreams. The opposite is true of sleep paralysis, where a person is fully conscious but finds themselves unable to move.
It is estimated that as many as 40 percent of people experience sleep paralysis. Another very common phenomenon is sleep hallucinations, which are vivid hallucinations of hearing or seeing when one first falls asleep. In addition, sleepwalking, narcolepsy, and the controversial near-death experiences and alien abductions may also be sleep disorders that result from a blurring of the line between sleep and wakefulness.
The “tug of war” between sleep and wakefulness
When we are sleep deprived or sleep deprived, we tend to stray into the limbo between sleep and wakefulness. For example, in Dingus’ experiments, although the sleep deprived subjects appeared to be awake, they may have actually gone into a brief drowsy state. This brief “snooze” usually lasted 0.5 to 2 seconds, and the longer the sleep deprivation time, the more frequent the phenomenon.
In the end, the subjects were completely unable to wake up from this brief “snooze”, so they fell into a deep sleep. “This is an outward expression of the ‘tug of war’ between sleep and wakefulness in the nervous system of the brain: part of the nervous system wants to sleep, while the other part of the nervous system tries hard to stay awake.” Director Wang Guoping said.
Some people are more likely than the general population to fall into brief periods of lethargy. Dingus and his colleagues found that people vary greatly in their ability to resist the temptation to sleep when they are tired. In healthy people who get enough sleep, the difference is small; however, in people who are deprived of sleep, the difference becomes very large. Recognizing this difference has important implications, especially in industries where the need to stay awake is a life-threatening matter.
If you’re driving down the road at 100 km/h, all it takes is a brief half-second of drowsiness for your hands to lose control of the steering wheel, and a brief 2-second drowsiness can cause your car to go completely out of control. According to statistics, more than 20 percent of traffic accidents are related to fatigue driving. Therefore, scientists recommend that for those jobs that require a high level of wakefulness at all times, practitioners are subjected to rigorous wakefulness tests on a regular basis.
Brain imaging studies reveal that some people can remain alert despite sleep deprivation because they have a mental back-up system. While people’s brain activity usually decreases when they are tired, these people are more capable of resisting drowsiness and can work to maintain brain activity. More interestingly, they will also develop the use of other areas of the brain as a backup to stay awake for long periods of time.
Scientists believe that these people have a special gene that gives them a greater ability to resist the effects of sleep deprivation. Such people may also be less prone to situations where they hover on the edge of sleep and wakefulness. However, this theory has yet to be confirmed.
”There are also people who are more prone to insomnia than the general population. These people are in a constant state of high arousal and seem to be extremely alert 24/7, not only at night than the average person, but also during the day.” Director Wang Guoping said studies have shown that their metabolic rate and levels of the stress hormone cortisol are higher than those of the general population.
Some people use the brain to “snooze” to get away with it
”The idea that there is a blurred line between sleep and wakefulness is becoming more and more accepted. Researchers are using a variety of instruments to capture the brain’s brief lapses and wanderings between sleep and wakefulness.” For example, U.S. neuroscientist Tononi uses an EEG recorder with 256 electrodes (commonly used EEG recorders have only 32 electrodes) to monitor the brain’s transient “snoozing” activity, says Director Wang Guoping.
He believes that brief states of lethargy are only the tip of the iceberg, and that some parts of the brain may “drop out” without us even realizing it, and that amnesia and daydreaming may be examples of this, and even some criminal behavior may be caused by it. For example, in 1988, a Canadian man was tried in court for the attempted murder of his parents-in-law. However, he was eventually found not guilty on the grounds that he was sleepwalking at the time. Since then, many defendants have sought exoneration on such grounds.
And the nature of the work of pilots and other professionals requires them to stay highly awake, so every so often they are subjected to lucidity maintenance tests. In a dimly lit room, they sit in a comfortable chair and remain awake for 40 minutes and repeat it four times over an eight-hour period. If they enter a brief drowsiness during the test, it can be detected by EEG, or by observing phenomena such as eye movements and relaxation of the jaw muscles.
However, such tests are not perfect, and sleep scientists see the need for more precise testing methods. For example, one test requires subjects to press a button after the light comes on, and their wakefulness is tested by repeatedly testing their reaction time. The researchers say this method is “incredibly sensitive” for testing the borderline state between wakefulness and sleep. The test method has been tried on astronauts on the International Space Station. It could be used in the future to regularly test pilots, nuclear power plant operators, and other professionals who must remain highly awake.
”In fact, the exploration of the boundary between sleeping and waking may allow us to finally figure out the nagging question of ‘why do we sleep?'” The dominant theory holds that sleep plays an important role in consolidating memory, says Director Wang Guoping. However, the two Italians with sleep disorders mentioned at the beginning of this article showed no signs of memory loss. Does this mean that sleep simply allows us to recuperate and rejuvenate?
If we can put aside the traditional concept of “black or white” between sleeping and waking, and use more accurate instruments to monitor brain activity, I believe we can finally unravel the mystery between sleeping and waking.