Sleep is a basic need, which allows us to maintain a healthy metabolic-organic correlation. If we do not respect adequate hours of sleep and the quality of rest, it can be harmful to our health.
Rest is an important and determining factor for the well-being of the entire organism. When we sleep, not only does the entire body recover and restore itself, but basal energy levels are also re-established.
Although the number of hours a person needs to sleep varies depending on the activity they perform and the stage of life they are in, the ideal is for adults to sleep between seven or eight hours a day.
“Studies show that not getting enough sleep or having poor quality sleep on a consistent basis increases the risk of high blood pressure, heart disease and other medical conditions.”
-National Heart, Lung, and Blood Institute (NHLBI)-
Phases or stages of sleep
Sleep phases can be classified into two categories: NREM and REM ( rapid eye movement ). Sleep is divided into 90-minute cycles, alternating between NREM and REM sleep; there are usually five cycles per night. Specifically, the NREM ( not rapid eye movement ) phase has four subphases.
“Thanks to sleep studies conducted over the past few decades, we now know that sleep has distinct stages that progress cyclically throughout the night. The brain remains active during sleep. However, different things happen during each stage.”
-National Heart, Lung, and Blood Institute (NHLBI)-
NREM phase
- Initiation of sleep
This is the initial phase of sleep that can last between five and ten minutes, as it is easy to wake up. All the muscles in the body relax completely and brain activity decreases.
- Beginning of the dream
This is the second stage, where body temperature and heart rate decrease significantly. This is the stage in which the body prepares to enter deep sleep and there is a slowdown in brain and muscle activity.
- Slow wave sleep
These are the third and fourth stages, which are characterized by the individual having a deep sleep and it is more difficult to wake up. In addition, brain and muscle activity decreases significantly. During these stages, the body is responsible for repairing tissues, building muscles and bones, and helping to strengthen the immune system .
REM phase
During this phase, characterized by rapid eye movement, dreams occur. Brain activity is rapid, muscles are paralyzed, heart rate and breathing accelerate, and extremely intense dreams can occur.
Approximately 90 minutes after falling asleep, the REM stage occurs, which lasts about ten minutes. As the hours pass, the REM stages lengthen until they reach an estimated time of one hour.
The importance of sleep for the body
It is not only the number of hours of sleep that is important but also the quality of the rest. Sleeping fewer hours means facing the day with less capacity to maintain attention, store memories in our memory, or access them. In addition, the amount of physical work that we can do will also be affected.
Sleep quality is associated with clarity of thought, the ability to respond to external stimuli, and also to encode information so that it can lead to a memory. This happens because a kind of restoration of the cognitive system occurs while we sleep.
The National Heart, Lung, and Blood Institute report that cutting back on quality sleep by one hour can make it difficult to concentrate the next day and slow response times.
By “stealing” hours of sleep, individuals will be more likely to perform poorly at school, work, and even when driving. In addition, their mood will be significantly affected, making them more prone to irritability. Likewise, those who suffer from chronic sleep deprivation will be more likely to suffer from depression.
In short, getting the right amount of sleep is essential to maintaining a high quality of life and enjoying overall health at any stage of life.