Have you ever wondered what happens to your body while you sleep? When we fall asleep, our body goes through different stages that make up the sleep cycle, that is, our body does not fall into a state of lethargy, on the contrary, it continues to function and performs countless important functions for health such as balancing our psyche.
During sleep, body movement is interrupted, alertness is turned off, and sensory faculties are greatly reduced. Sleep is a physiological necessity, so it should come as no surprise that important actions such as hormone secretion and mood regulation occur during sleep. We have heard a lot about the importance of sleeping well, but we understand little about this process, for this reason we invite you to know what the sleep phases are and what happens in each one of them.
What are the phases of sleep?
Sleep is far from being a state of calm and tranquility, even if we feel like it. The truth is that once our body falls asleep it begins to go through different stages that make up a cycle, the sleep cycle. To begin to understand how sleep works, it is important that you know that during eight hours of sleep different cycles of approximately 90 minutes are repeated and each of them is made up of different phases and types of sleep.
When explaining sleep we must say that there are two stages, the non-REM sleep phase, slow sleep, and the REM sleep phase, deep sleep. However, the first of these phases is divided into four distinct phases. That said, let’s know what the sleep phases are and what happens in each of them:
The first phase of the sleep cycle is also known as the drowsiness stage and perhaps the only one that we can easily identify, since we have all experienced it while still conscious. In this phase, the first 10 minutes of sleep take place and it is a kind of wakefulness from the moment we begin to feel like resting until we are asleep.
In this phase we still perceive all kinds of auditory and tactile stimuli, sleep is light and little or not at all restorative, eye movements are slow and muscle tone begins to decrease.
When we are going through phase II of the NON-REM stage, our nervous system has already blocked our ability to capture sensory stimuli, which allows us to completely isolate ourselves from where and when we are to start preparing for a deep and restful sleep .
In phase II, sleep does not promote total rest and, unfortunately, this phase comprises 50% of the entire sleep cycle of most adults. Eye movements have already stopped in phase II and muscle tone is much lighter.
Phase III is well known because DELTA sleep takes place in it and the sensory block becomes total. At this stage we are not dreaming yet, the body’s blood pressure decreases by up to 30%, breathing becomes lighter, growth hormone is produced, and muscle tone is lower than in phase II. When we wake up in phase III, it is common for us to experience disorientation and confusion.
This is the last phase of the non-REM stage and the one with the greatest depth of sleep and corresponds to 20% of the sleep cycle. This is the most important phase, as it determines the quality of your sleep, so in this part of the cycle brain activity is much slower, since DELTA activity predominates.
This phase is essential for the recovery of the psyche and the energy of the organism. If there is a deficit in phase III or IV, the person is likely to be drowsy during the day. In phase IV, muscle tone is even more reduced, it is not where the person usually dreams, but where sleepwalking and night fears are manifested .
In this phase, the total relaxation of muscle tone occurs, but the central nervous system is already active before any alert, for this reason the REM phase is known as the paradoxical sleep phase. It is at this stage of the cycle that dreams occur and the electrical activity of the brain is rapid. The REM phase represents 25% of sleep, it can last between 15 and 30 minutes and during this time constant eye movements occur under the eyelids. This phase is the end of a 90 minute cycle. During a night of sleep we can have up to five sleep cycles.
All human beings have circadian rhythms, which are nothing more than biological cycles that help us regulate the way we rest. These rhythms are synchronized, in most people, with the cycle of the environment, which means that when night falls our body begins to prepare for sleep, because it knows that bedtime is approaching and, therefore of course, to rest. In the same way, when we wake up and see the sunlight, our brain immediately knows that on a new day and that there is much to do, then we wake up with energy.
The above described is an ideal scenario, wake up with the sunlight and sleep with the moonlight. Unfortunately, this is not always the case. If there is an imbalance in our circadian rhythm, such as when we travel to another country with a different time zone, our body tries a bit to adjust and we suffer negative consequences that affect sleep such as jet lag.
To prevent this from happening, it is important to have excellent sleep hygiene, respect the cycles, and let the body go through each of the phases until complete rest is achieved. In addition, we must remember that our body activates the production of hormones during nighttime sleep, therefore, if it is of poor quality or does not take place during the correct circadian cycle, we can begin to notice negative consequences on our health due to bad habits. when sleeping.
Hello Readers, I am Nikki Bella a Psychology student. I have always been concerned about human behavior and the mental processes that lead us to act and think the way we do. My collaboration as an editor in the psychology area of Well Being Pole has allowed me to investigate further and expand my knowledge in the field of mental health; I have also acquired great knowledge about physical health and well-being, two fundamental bases that are directly related and are part of all mental health.