What is Sleep?

At its basic definition, sleep is the bodily condition that is marked by a period of rest that recurs over a specific interval of time that is stretched over the course of a few hours. Yet this description merely touches on the general concept of sleep and does not break down its necessary purpose or its overall importance.

A Trio of Components

In essence, the actual occurrence of sleep itself is defined by three distinctive components:

  1. A state of altered consciousness - When someone enters the sleeping phase, they become completely unaware of their sense of space or surroundings.
  2. A general blockage of essential sensory activities - The key functions that pertain to a person's sense become inhibited during sleep. These functions would pertain to activities related to sight, hearing, taste, touch, or smell.
  3. An inhibition of all muscles that are not charged with internal regulatory purposes - All muscular structures that are responsible for voluntary bodily functions are subdued. These muscles are different than other muscular structures that are responsible for activities pertaining to the preservation of life, such as the heart muscle.

Purpose of Sleep

At its basic core, the purpose of sleep is to rejuvenate the body in such a way that a person feels a sense of bolstered energy and a greater sense of functionality upon returning to a state of wakefulness. However, this process of rejuvenation can be deconstructed to a more complex level.

When sleep occurs, the various systems that are charged with the regulation of a person's body are placed into a highly anabolic state. What this means is, the body reaches a peak period in which metabolic processes pertaining the synthesis of proteins occur. This elevated protein synthesis is tied to regulatory functions linked to the immune, nervous, skeletal, and muscular systems, thus leading to the notion that the sleep is an essential factor for process related to growth, development, and overall maintenance to occur. It has been shown through scientific research that this rate of systematic increase occurs in other animals including insects.

How the Body Alters During Sleep

The inhibition of certain bodily functions that occurs during sleep has specific ramifications on several other processes and the rate at which they have been shown to operate. These ramifications tend to fluctuate depending on what stage of sleep the person is in.

For example, the body temperature of a person will gradually drop depending on what stage of sleep is being experienced, with REM sleep being the part of the cycle in which temperature reaches its nadir. Conversely, the breathing mechanism becomes significantly more regulated during the stages of non-REM sleep, dipping below the rate of breathing that is typically associated with a state of wakefulness. However, when a person achieves REM sleep, the pattern of respiration becomes significantly more variable.

A person's cardiovascular system will also experience a heightened state of activity during REM sleep, after achieving a lower yet more consistent pattern of function during the stages of non-REM sleep. The elevated heart rate that can be achieved in this stage of sleep causes an increase in cardiovascular system related activities such as a boost in blood pressure, heart rate, and the flow of blood. It is currently unknown as to why these particular processes fluctuate during the course of REM sleep.

Sleep and Brain Activity

It had been thought for centuries that sleep had a direct link to brain inactivity; that it was a time when the brain could lower its functionality as a means to provide a renewed sense of capacity during wakefulness. However, it has been proven over the course of the last sixty years or so that this in fact is not the case. Rather, it is has been shown that the brain attains an active state during the sleeping process. That being said, the style and pattern of brain activity does change noticeably between wakefulness, non-REM sleep, and REM sleep.

The level of activity is linked to the firing of neurons; electrically excitable cells that process and transmit information through electrical or chemical signals via synapses. During periods of wakefulness, this process of neuron firing is faster than what is experienced during non-REM sleep. However, it is also shown that non-REM sleep produces a pattern of neuron firing that is significantly more coordinated and synchronous. However, it has been shown that the brain's capacity to fire neurons during REM sleep can be heightened even more than it is during periods of wakefulness. This reason for this boost has been theoretically tied to brain activity as it pertains to the level of intense dreaming that could occur during this particular stage.

The Importance of Sleep

The various activities that have been shown to occur during the process of sleep help to reiterate how crucial it is for a person to attain a proper amount of sleep on a nightly basis. Not doing so can do more than simply making a person tired. It could actually have serious affects to a person's demeanor, health, and ultimately life. As such, the process of sleep could almost be viewed as an internal defense mechanism, protecting the body from becoming weak and susceptible to disruptions in homeostasis both internally and externally.

The range of negative effects that are tied to a consistent lack of sleep can run the gamete from minor issues, such as severe yawning and being irritable, to major problems, such as an increased risk of heart-related death, an elevated risk of Type-2 diabetes, and obesity. Yet these risks can be subdued by consistently maintaining the proper level of sleep on a nightly basis. In the case of adults, the proper range that constitutes a proper night's sleep is 7 to 9 hours.

While it may be easy to define sleep as getting rest or 'shutting down,' the reality behind sleep is that it is one of the most vital things a person can do to obtain an optimal amount of energy and, ultimately, an optimal level of health.