What is microsleep and why can it be dangerous?
Have you ever caught yourself "switching off" for a second and then suddenly waking up? Perhaps you were driving, listening to a lecture, or working on your computer, and suddenly — bam! — your consciousness seemed to blink. This is microsleep, a short and insidious lapse into unconsciousness. In this article, we will look at what microsleep is, why it happens, and how it can be dangerous.
Scientists have long established that the optimal duration of sleep is 7-8 hours per day. A huge number of studies have shown that lack of sleep or lack of sleep is dangerous for the body. They not only lead to poor health, decreased cognitive abilities and attention. Lack of sleep contributes to the development of such ailments as psychosis, obesity, type 2 diabetes. The entire body suffers, including the immune system, which is vital for each of us.
We clearly distinguish between sleep and wakefulness. But scientists say that everything is much more complicated. Neurobiologists have found that the brain can "sleep" when we don't even suspect it. These states are called microsleep and local sleep. Most of us encounter these phenomena regularly, but we don't know their nature.
Many people believe that when we fall asleep, our brain "switches off." But this is not true - sleep affects only some parts. And even then, they do not stop working, but become less active. Scientists recorded the electrical activity of the sleeping brain and saw so-called delta rhythms. These are slow waves with high amplitude that roll synchronously throughout the brain.
During one second in a state of sleep, 1-2 oscillations occur, which is several times less than when awake. When a person is in a state of deep sleep, this is clear even without an encephalogram. But there are other types of sleep that do not look obvious at all. Microsleep is one of them.
We all know what it is. Many have observed how a person's eyelids slowly drop, his head gradually bows, and then he suddenly shudders, as if he was pricked. This can often be seen at boring lectures, in transport or in offices where employees are busy with monotonous work. This is what microsleep looks like - a state lasting from 0.5 to 15 seconds.
This is a very insidious condition, as often a person does not even notice that he fell asleep. It seems to him that he was just distracted for a moment. But an encephalogram taken at this moment clearly shows a slowdown in the rhythms of the brain, characteristic of sleep. The state of microsleep is not always associated with fatigue. It also occurs in well-rested people if they are forced to do something monotonous, boring.
Neurobiologists conducted an experiment in which they placed volunteers in an MRI machine. They were asked to track the movement of a small object on the display, accompanying it with a cursor controlled by a joystick. Most of the participants fell into a state of microsleep an average of 36 times in 50 minutes, lasting 1-3 seconds. However, they themselves did not notice it.
At this time, scientists tracked the behavior of different parts of the brain. They found out that during microsleep, the activity of the thalamus, responsible for transmitting information from the outside world to the cerebral cortex, decreased. But the activity of the frontal parts of the brain increased significantly. They are responsible for cognitive abilities. Therefore, the researchers concluded that this area of the brain tries to overcome falling asleep and brings a person out of the state of microsleep.
In 2011, neurobiologists were in for an even more unexpected discovery. Under the direction of Professor Giulio Tononi, a series of studies were conducted that showed that some groups of neurons in the brain can sleep while a person is apparently awake. This phenomenon was given a special name - local sleep.
It is more difficult to detect than microsleep, as it requires monitoring the activity of individual neurons rather than the overall electrical activity of the brain. This is currently impossible to do without invasive intervention. For this reason, local sleep is studied in laboratory animals, most often rats.
When the brain is awake, neutrons are extremely active. During normal sleep, groups of neurons fall silent for a short time, no more than 0.5 seconds, and then start working again. Scientists call this temporary freezing the down state. This "falling asleep" of neurons does not happen simultaneously in all areas of the brain. Some group of neurons simply "decides" to fall silent for a split second, and then starts working again. Then this can happen in another part of the brain.
Surprisingly, local sleep, unlike microsleep, does not affect a person's external condition. The brain continues to perform its functions as usual, while groups of neurons take turns resting. Professor Giulio Tononi's team wanted to find out whether local sleep is associated with lack of sleep or overwork. The experiments were conducted on rats.
The experimental animals were not allowed to fall asleep. They were disturbed and overloaded with impressions, new toys were thrown to them and various stimuli were applied. This lasted for 4 hours, after which it became clear that the stronger the rats' need for sleep, the more actively the number of local sleep episodes increased. When the animals were allowed to rest, neural activity quickly returned to normal.
Scientists have concluded that local sleep is a natural mechanism that allows neurons to rest in turns in extreme conditions of sleep deprivation. But they have discovered another unpleasant fact. Sleep-deprived rats with a large number of episodes of local sleep were given simple tasks. For example, the animals were asked to get a treat through small cracks.
It turned out that local sleep affects the brain's abilities and the rats were less attentive and often lost food. So, alternate rest of neurons does not relieve the body of the need for normal sleep and a tired brain is less productive and makes more mistakes.
But let's return to microsleep, during which a person can lose control of the situation for a short time. This is especially dangerous for pilots, train drivers and drivers. If they switch off for a moment, they risk getting into an emergency situation that is fraught with human casualties. What should be done to avoid danger?
Neuroscientists recommend getting enough sleep and avoiding night shift work, of course, as much as possible. If you feel tired, it is better to put everything aside and lie down to sleep for at least 15-40 minutes. Such sleep will significantly increase vigor and reduce the likelihood of microsleep and local sleep.
A 1994 NASA experiment found that pilots who slept for just 40 minutes before takeoff experienced microsleep four times less often than those who were sleep-deprived. But the researchers also found that energetic music, loud conversation, and movement were the last resort.
Sleep remains one of the most mysterious functions of our body, and its unexpected manifestations, such as microsleep and local sleep, remind us of the importance of proper rest. It seems incredible that the brain can fall asleep in parts right in the middle of active wakefulness - and yet, it is a fact. Have you encountered microsleep? Maybe you noticed how you “switch off” while driving or at work? Share your stories in the comments - it will be interesting to know how you cope with this insidious thing!