The science of dreams and nightmares: What happens in our brains when we sleep?

Last night you might have slept Seven or eight hours. You’ve probably gotten an hour or two of deep sleep, especially if you’re young or physically active. In fact, sleep It changes with ageAnd Physical exercise It affects brain activity. I also got about three or four hours of light sleep.

The rest of the time, you’re probably in paradoxical sleep (REM). Rapid eye movement). Although this is not the only time the brain dreams – it is possible during other stages – the brain activity is more likely to be remembered and we can tell.

It could be because strange thoughts or feelings wake us up or because the last hour of sleep consists almost entirely of… Paradoxical sleep. When a dream or alarm wakes us, we generally emerge from paradoxical sleep and the dream images can stay with us for a few more minutes. Then we keep his memory.

If the dream is strange or interesting, you can talk about it with someone else, which will help you understand it better.encoding in the memory.

Dreams and nightmares are mysterious, and we’re still learning about them. They increase our brain activity, clarify ideas about the day’s events at a molecular level, and can help us imagine what is possible during our waking hours.

Read more: Being chased, losing your teeth, falling… What does science say about recurring dreams?

What do scientists know about REM sleep and dreams?

It is very difficult to study dreams because you cannot observe what happens when people sleep. Brain imaging has revealed that some Brain activity patterns They are associated with dreaming (and the stages of sleep most closely associated with it). But these articles rely on personal accounts of the dream experience.

Anything you spend a lot of time on probably achieves multiple goals.

At a basic physiological level, all mammals dream (as he pointed out Brain activity, sleep behavior, and studies of consciousness) – Even the platypus and the echidna may experience something similar in a dream (provided their bodies are symmetrical) Good temperature). We can see the similarity between their brain activity and their sleep stages Paradoxical sleep of a person.

This is not the case for less developed species. some Jellyfish Those who do not have a brain experience what might be described as sleep at a physiological level (depending on their position, their calmness, unresponsiveness, and rapid “waking up” when necessary), but without the physiological and behavioral elements reminiscent of paradoxical sleep.

In humans, REM sleep occurs cyclically, every 90 to 120 minutes throughout the night. It prevents us from deep sleep and being present Vulnerable to attacks. Some scientists suggest that we dream to prevent our brain and body from catching a cold. Our core temperature is normal Higher during these stages of sleep. If one has to react to external cues or dangers, it is easier to wake up In the middle of a dream than it was at other times.

During paradoxical sleep, the brain goes into active mode for a certain period, like a telescope that gives access to consciousness by allowing us to observe what is happening on the surface, and come back if all goes well.

Some data suggests that “fever dreams” are much less common than we think. In fact, we make less Paradoxical sleep stage When we are feverish, even if our dreams tend to be as well Darker and eerie.

The fact that less time is spent in paradoxical sleep can be explained by the difficulty of regulating body temperature during this stage. To protect us, the brain tries to regulate our body temperature by “skipping” this stage of sleep. This is also for this reason We generally dream less when it’s hot.

Deep cleansing of the brain

REM sleep is important for healthy brain function, as studies using it have indicatedElectroencephalogram To measure brain activity.

In the same way that deep sleep helps the body regain its physical capabilities, sleep is dreaming “rinse” Our neural circuits. At the molecular level, the chemicals that support thought are distorted by everyday cognitive activity. Deep sleep allows them to return to their initial form. The brain is “wash” Through cerebrospinal fluid, which is controlled by the glymphatic system.

On another level, REM sleep “brings order” to our recent memories and feelings. during This stageOur brain integrates procedural memories (how to accomplish a task) and emotions. the Other stages Sleep, in which we dream less, is important for consolidating episodic memories (events).

As the night progresses, our cortisol production, Stress hormone, He increases. It is thought that the amount of cortisol may affect the type of memories we consolidate and perhaps the type of dreams we have. This means that late-night dreams tend to be more common More fragmented or strange.

Different types of sleep allow you to do this Consolidation Useful brain activity today and eliminate less important information.

Random thoughts, reorganized feelings

This shuffling and undoing of the day’s activities happens while we sleep. This is why we often dream about things that happened During the day.

Sometimes thoughts and feelings are reorganized and eliminated “Trash can” During sleep we can experience consciousness. Random thoughts and feelings are mixed together in unusual and wonderful ways. The fact that we are aware of this process can explain the strangeness of some dreams. Our daytime experiences can also lead to nightmares or disturbing dreams after a Traumatic event.

It seems like some dreams Predict the future or carry strong symbolism. In many societies, dreams are a window into a world Alternative reality Where different possibilities can be considered.

Do dreams have meaning?

we’ve got Good understanding Thermal, molecular, and neural regulatory aspects of dreams. But its psychological and spiritual aspects are still largely unknown.

Maybe our brains are designed to try to make sense of things. Human societies have always interpreted random phenomena – such as the flight of birds, tea leaves, or planets – and searched for their meaning. Almost all human societies consider dreams to be little more than random neural performances.

The history of science teaches us that some phenomena once thought magical can later be understood and controlled, for better or worse.