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Global Observatory for healthy Sleep / The importance of sleep / What is sleep?

What is sleep?


Sleep is a complex physiological phenomenon which is essential for people's health

It is a universal process in the animal kingdom and is a basic need of our organism, allowing us to rest and recuperate, both physically and mentally.

Is characterised by changes in physiological activity, and by a lower response to external stimuli.


The function and purpose of sleep have yet to be fully elucidated; nonetheless, the relationship between sleep quality and the body's capacity to recover its health in response to certain serious and major diseases has been scientifically demonstrated.


Sleep disorders may also be related to major complications and certain illnesses, such as major depression, heart attack, fibromyalgia, rheumatoid arthritis, arthrosis and Alzheimer's disease, among others.




Stages of sleep


Sleep and wakefulness are two states of cerebral activity, which succeed each other cyclically.

Thus, in accordance with the brain's electrical activity, different sleep stages have been described, each one having specific characteristics:

Observatorio Global del Sueño

STAGE 1: Drowsiness
STAGE 2: Light sleep
STAGE 3: Deep sleep
REM: (Rapid Eye Movement) Phase

In adults, nocturnal sleep is normally organised into 5-6 cycles, each of 60-90 minutes. The effectiveness, distribution and overall percentage of the different stages provide information on the length and structure of sleep. The adjustment of these parameters to the normal values described is used to evaluate sleep quality.



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