How it feels: This state is the opposite of sleep paralysis — the consciousness is asleep, but muscle paralysis does not occur. In their sleep, people can walk, clean, or even leave the house, which is often very dangerous. In the morning, they don’t remember anything.
Why it happens: Somnambulism occurs in about 4.6-10.3% of the population, with children affected more often (source). The cause is still unknown, as are methods of treatment.
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How it feels: The person wakes up from a sensation of a loud explosion or a clap. Sometimes the sound seems deafening. It can be accompanied by an increasing buzz or a flash. The phenomenon is not dangerous, but it frightens people. Some think they have had a stroke.
Why it happens: This happens when, for some reason, there is a surge of neural activity in the areas of the brain responsible for processing sound (source). Sometimes the syndrome is coupled with insomnia or jet lag.
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How it feels: Sleep apnea is a sudden stop of breathing in a dream. The person wakes up as a result. The quality of sleep decreases, the brain experiences oxygen starvation, and it becomes difficult to get enough sleep. Arterial pressure also fluctuates during an attack, which may cause heart problems.
Why it happens: During sleep, the pharynx muscles relax, which sometimes leads to blockage of the airways. Obesity, smoking, and old age increase the risk. Fun fact in a world of anxiety: one may alleviate it by playing the didgeridoo, an Australian wind instrument (source).
How it feels: Probably everyone has had strange recurring dreams, which constantly reproduce the same plot.
Why it happens: Psychologists believe our brain uses such dreams to pay attention to something we didn’t notice in our daily life. These stories will return until the situation is resolved (source).
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How it feels: Sometimes we feel like we’ve been thrown onto our bed from high up. We flinch and wake up. Sometimes before that, we dream that we are flying or stumbling and falling — a rather unpleasant feeling.
Why it happens: Sleeping is similar to dying — the heartbeat and breathing slow down, muscle tone is reduced. The brain “gets frightened,” perceives this as a real death, and checks whether the person is alive, sending impulses to the muscles.
How it feels: This is a neuropsychological phenomenon during which a person, half-asleep and half-awake, sees himself from a place outside his body. For mystics and occultists, this confirms the existence of the soul.
Why it happens: The phenomenon is very difficult to study. While scientists know that the illusion of getting out of the body does exist, it is not clear how it works and why it arises. It’s also unclear how to deal with this. Yet some know how to enter this state deliberately. They do so to expand the boundaries of their cognitive capabilities.
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How it feels: Sometimes we can’t find a solution to a problem for a long time, and so we constantly think about it. And then, in a dream, the brain gives us a clue. Now the most important part is to remember it.
Dmitri Mendeleev, a Russian chemist, was obsessed with creating a periodic table of elements — and then he saw it in a dream. Something similar happened with the chemist August Kekulé when he dreamed of a formula for benzene.
Why it happens: Sometimes our subconscious already knows the answer, although it has not yet reached consciousness. During sleep, the subconscious is more active and could provide the insight. Sleep is great, but sometimes it comes with even more perks.