The importance of sleep

The importance of sleep

Sleep – its nature and functions

Sleep is a process that is universal for animals. It is defined as a physiologic and behavioral state characterized by partial isolation from the environment. It is actually a state of mind with altered consciousness, inhibited sensory perception and absence of activity in nearly all voluntary muscles.

Sleep has multiple functions: physical recovery, memory consolidation biomechanical refreshment and emotional regulation. Hence, a proper sleep routine is essential for a person’s well-being. However, it is a very fragile state, as our body maintains a cognitive function which will interrupt sleep. It is a defense mechanism, which is triggered by noise, touch or perception of pain. Constant interruptions in sleep can lead to sleep deprivation. It can be caused by either a lack of sleep duration or fragmentation of sleep cycles

Sleep and wake cycles

An individual’s 24-hour day is divided into sleep and wake cycles. For an average adult, it represents 16 hours of wakefulness and 8 hours of sleep. Of course, some people sleep more and some less. In humans, sleep is divided into two distinct categories: Rapid eye movement sleep (REM sleep) and non-Rapid eye movement (non-REM sleep). Sleep also follows cycles of, on average, 90-minutes duration where non-REM and REM sleep alternate in 5 stages. They are portrayed in the table below.

Four to six uninterrupted cycles for a good night’s sleep

Of the five stages, the first and second are considered as light sleep, with stages 3 and 4 ranked as deep sleep. The fifth stage represents the REM sleep. The REM is usually associated with dreaming. During this stage, muscle activity decreases, whereas as heart rate and brain activity increases. Augmentation of the later aspects may increase to rates higher than those experienced during periods of wakefulness. In simplest terms, the body enters a state of paralysis during REM stage. In fact, during such deep sleep, the sleeper’s dreams can involve graphic and fantastic imagery. It is also the stage where acted dreams can occur; potentially causing harm to the sleeper, and his/her partner.

In such, good night’s sleep usually contains four to six uninterrupted cycles. However, there exists a multitude of disorders that can interrupt sleep cycles which leads to detrimental effects on an individual’s health. This article will concentrate on one of the most damaging; the sleep apnea.

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