What Sleep Is All About

Several theories have surfaced explaining the many different reasons why we sleep. However, up to this point in time, the exact reason why we do it remains an elusive truth. Nevertheless, the importance of sleeping can neither be denied nor dismissed. Sleep is so important to each one of us that it warrants no surprise why sleeping aides have gained a considerable following in the market.
Before, scientists perceived that our brains' normal state is that of wakefulness, and sleep signifies a halting of our brains' activities. But persistent research combined with modern technology has confirmed that our brain does not become inactive in either stage. Moreover, it is continuously working albeit the use of diverse parts for each state.
Entering into Sleep Mode
The neurotransmitters located in our brains are chemicals that alert our nerves, determining if we are asleep or not by acting on various nerve groups, neurons, and cells—all of which are found also in our brains. The serotonin and noropinephrine transmitters are responsible for maintaining certain portions of our brain during the state of wakefulness. The aforementioned are produced by neurons found in our brainstems, which links our spinal cords to our brains. Certain neurons located at the base of our brains start to send signals once we fall asleep. In doing so, they turn off the signals that maintain our wakefulness. In addition, research has divulged that the presence of adenosine is what causes us to become sleepy. They accumulate in our blood as we are awake, and eventually, they would induce sleepiness.
What Happens When We Sleep
Generally, sleep is divided into five diverse phases: stages 1, 2, 3, 4, and rapid eye movement stage or REM sleep. Normal sleeping patterns would entail having to pass through each of these stages in chronological order until we reach the REM sleep. Because sleep is in a cycle form, upon reaching the latter, we would then be back to the drawing board, beginning with stage 1. It has been determined that we spend half of our entire sleep in stage 2 and only 20% in the REM sleep. The remaining 30% are distributed among the remaining stages: 1, 3, and 4. This sleeping pattern is differentiated among infants who spend half of their sleep in the REM sleep. Below are the various sleep stages and a brief overview of what goes on in each:
Stage 1
This is the stage in which we are on the verge of falling asleep. Slowly, our muscles begin to relax. Coinciding with the latter, our eye movements also slow down. Because this stage is characterized by light sleep, we can be easily awakened.
Stage 2
Entering stage 2 is marked by an absolute stillness of our eyes as they have finally stopped moving. With this, our brain waves slow down but quickens occasionally. Sleep spindles is the term used for these bursts of rapid movements.
Stage 3
Exceedingly slow brain waves called delta waves start to surface as we enter stage 3, which are bestrewn with faster, smaller waves. This is the beginning of deep sleep where there are neither eye movements nor any muscle activity. From this stage onwards, awakenings would be difficult.
Stage 4
Upon reaching stage 4, our brains produce no other kind of brain waves except delta waves. Deep sleep continues to this stage.
REM sleep
Moving into REM sleep, our breathing speeds up and becomes more shallow and irregular. Along with our breathing, our eyes start to move rapidly in different directions as our limbs become absolutely immobilized. These changes coincide with an increase in our heart rate and blood pressure. During this stage of sleep, men tend to have erections. More often than not, people who awaken during the REM sleep are able to recall their dreams.