Sleep 101: The Basics of Sleep

Sleep that knits up the ravelled sleave of care
The death of each day's life, sore labour's bath
Balm of hurt minds, great nature's second course,
Chief nourisher in life's feast.
~ William Shakespeare, Macbeth

Sleep is the balm for our weary bodies and spirits. For what is sleep but a physical and mental resting state in which a person becomes relatively inactive and unaware of the environments. It is characterized by a general decrease in body temperature, blood pressure, breathing rate and most other bodily functions.

Sleep is a necessary and vital biological function. It enables the body to rejuvenate, reenergize and restore. It ensures the normal functioning of all the systems in our body, including the nervous system and immune system. Sleep enables the brain to regenerate brain cells to boost our memory and ability to carry out mathematical calculations.

It is also during sleep that release of growth hormone in children and young adults takes place. Sleep likewise helps maintain the optimal functioning of our emotional and social aptitude by giving rest to our brain and other organs in the body.

Sleep is actually a dynamic process with two different states that alternate in cycles during a night’s sleep. Sleep consists of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. NREM is further subdivided into four stages: Stage I (light sleep), Stage II and Stage III and IV (deep sleep).

Approximately 75 percent of the sleep cycle is spent in non-REM sleep. Stage I is a stage of light sleep and is considered a transition from wakefulness to sleep.  This stage could be termed the "dozing" stage.

Stage II occurs throughout the sleep period. This stage is often considered the official onset of consolidated sleep.

At Stage III, sleep advances progressively deeper making an individual difficult to arouse. Stage 4 is characterized by very deep sleep. People who wake during deep sleep often feel groggy and disoriented for several minutes.

REM sleep, on the other hand, represents 20 to 25 percent of the total sleep time and is usually associated with dreaming.

Sleep essential to a person’s physical and emotional well-being. Infants have an overall greater total sleep time than any other age group. Adults need an average amount of six to eight hours per day. Towards old age, people tend to sleep more lightly and for shorter periods of time.