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What is a Sleep?
A healthy sleep is when the nervous system is inactive, eyes are closed, postural muscles relaxed and consciousness nearly suspended. It is known as the Sustained Quiescence State that is accompanied by reduced responsiveness to external stimuli, quick reversibility to the wakeful condition, characteristic EEG (electroencephalogram- electrical activity in the brain) changes in different stages and spontaneous occurrence with endogenous periodicity (Circadian Rhythm).
Know about the Sleep stages:
While sleeping, we pass through five stages of sleep namely- Stages 1,2,3,4,5 and REM (Rapid Eye movement) sleep. All these stages form a cycle beginning from stage 1 and ending at REM sleep, and again moving onto to Stage 1. You must be surprised to know that we spend approximately half of our total sleep time in Stage 2 and around 10% in REM sleep and other stages. However, infants spend more than 50% of their sleep time in REM sleep.
Stage 1- This is a “Light Sleep” stage, where we can easily be awakened. The movement of eyes and its muscle activity is slow. It is possible that people who experience this tend to remember vague visual images. Often people will also have a sensation of falling, where there will be a sudden startling movement.
Stage 2 – In this stage, there is a decreased movement of eyes and brain fluctuations become slow, leading to frequent bursts of sleep.
Stage 3 and 4– This stage is characterized by slow brain movements coinciding with faster waves. It is impossible to wake someone in these stages as together they are called as Deep Sleep. The eye movements and muscle activities are NIL. Usually, if a person is awakened during sleep tend to feel irritated and heavy for a few hours. There can be situations when children can experience bedwetting, and sleep walking.
How much sleep is required?
Neurologically, it is difficult to determine the number of hours that are required for a healthy sleep. Some people are active with only 3-5 hours of sleep per night, while some need atleast 8 hours of sleep or more to perform effectively. Please understand your sleep requirement and take adequate amount of sleep. Do not consider daytime sleep as complimentary of nocturnal sleep deprivation. Afternoon nap only relaxes you physically for prolong sleep deprivation but it will not be useful for complete physiological functions of sleep.
Why we sleep:
Sleeping is not a passive process and it is associated with several active functions like healing, memory consolidation, hormonal balance and growth. Internal Repair and pain pathway maintenance are some of the other functions of sleep while Pain defensive pathway is activated only with good quality of sleep. You must know that sleep is not putting mental and physical activities on hold but a second state where mental and physical activities are complex.
It has been observed that lack of sleep can cause damage to arteries and lead to heart problems. People who are not getting enough sleep risk getting obese due to decrease levels of Leptin a hormone that at mealtime signal the body you are full. People who are sleeping less, snoring more, tossing and turning eyeing the clock, praying in dawn- are more fatigued and literally aging them before time”. Below are few disorders caused due to lack of sleep: