In the past, people believed that the brain and body became dormant when we sleep. However, advanced research in the late 20th century proved that there was a lot going on in the background. While the new discoveries should have settled the question of what happens when we sleep, it resulted in more questions and debates. Different theories have since emerged, with some stating that our consciousness is transferred to another dimension. Here is what we think actually happens when we sleep from a scientific point of view.
The Different Types of Sleep
To best figure out what happens when somebody sleeps, it’s important to note that there are two types of sleep. There is the Rapid-Eye Movement (REM) and non-REM sleep. When you go to bed, you begin with non-REM sleep, which is divided into four stages.
The first is the limbo between being asleep and awake. It’s when the brain is aware of its surroundings. The second stage is light sleep, during which the breathing and heart rate drop slightly. Finally, there is the third and fourth stages, where a person falls into deep sleep, and all organs fully relax.
The other type is REM sleep. This is when the eyes move rapidly behind the lids. REM sleep isn’t relaxing because, in this type of sleep, the brain waves are as active as when awake. Also, the body temperature and heart rate increase. Throughout the night, humans undergo several cycles of non-REM and REM sleep.
So, What Happens When We Sleep?
Different parts of the body undergo varying experiences when we sleep. For instance, breathing and heart rate slow down during the last two stages of non-REM sleep. On the other hand, the pulse shoots up as you enter REM sleep.
The strangest thing that occurs during both types of sleep is how the muscles relax. The deeper somebody goes into the stages of non-REM sleep, the more relaxed the muscles become. In REM sleep, humans experience atonia, where the muscles become paralyzed. This is actually a defense mechanism that prevents the arms and limbs from moving frantically when one is dreaming. However, in REM, the eye muscles remain to be very active.
During sleep, the body produces a wide range of beneficial hormones such as cortisol, which alleviates stress, the growth hormone, and melatonin. Interestingly, when sleeping, the body deactivates the cough reflex. Therefore, most people rarely cough, especially in REM sleep. It may only occur due to obstructive sleep apnea.
Other things that happen during sleep are the consolidation of memories and lesser urine production by the kidneys. This explains the minimal to no bathroom breaks at night.
Do Brain Activities Stop When We Sleep?
Contrary to what most people assume, brain activities continue even as we sleep. During the first two stages of non-REM sleep, brain activity appears to decrease. However, in stages three and four, there are numerous short bursts of brain activity.
As a person cycles into REM sleep, brain activity increases drastically. Scientists have identified that this increase in brain activity causes vivid dreaming in REM sleep. It’s when people experience highly realistic and bizarre dreams. Note that dreaming can also occur in other stages of sleep and is not limited to this stage. Only the intensity of the dreams changes depending on the type and stage of sleep.
Factors That Affect the Quality of Sleep We Get
Two main things control sleep. The first is the circadian rhythms, the light cues that trigger the brain to fall asleep when lights are switched off.
Then, there is the sleep drive that naturally occurs in our bodies. After a long day, your mind and body automatically urge you to go to bed and rest. Therefore, an issue with either can affect a person’s sleeping experience.
What Happens to People with Insomnia?
Obviously, not everyone gets the full 8 hours of sleep. So, what happens to people who have insomnia? As expected, they spend most of their time awake, negatively affecting their sleep patterns. They may not go through all the four or five cycles between REM and non-REM sleep. This leads to bad mood and sleepiness during the day.
Scientists have also observed that people with insomnia mostly spend time in REM sleep, so their brains don’t rest well. As such, they often wake up feeling irritable, anxious, and even depressed. The same side effects will occur for people who sleep too much. Hypersomnia is known to cause daytime sleepiness and difficulty in concentration.
Why Do Some People Snore When Sleeping?
Something that happens when people are sleeping and is often ignored or not talked about enough is snoring. It occurs when air can’t easily flow into the affected person’s mouth or nose. Luckily, as long as snoring is mild, there is no cause for concern.
However, excessive snoring may indicate a condition called sleep apnea, which not only disrupts sleep patterns but can minimize the amount of oxygen going to the heart, leading to heart disease.
Conclusion
So far, this is all we know about what happens to the body and brain when someone is asleep. Fortunately, sleep science is advancing at a significant rate. In the next decade or so, there’ll be more information about what happens when we sleep. Research may even answer the long-researched question about where dreams come from. All said, the best thing one can do is ensure they get enough sleep every night.