Why is sleep important and what happens when you don’t get enough?
Sleep is a nonworking state of consciousness characterized by general unresponsiveness to the environment and general physical immobility. Sleep important for health and memory development.
Why Is Sleep Important?
Every one sleeps, sleep is an altered state of consciousness. Sleep has biological basis and psychologists consider it as a behavior. Because lack of sleep so directly effects other behaviors, psychologist studies it intensely. Although a great deal is known about what happens psychologically when we sleep, we do not yet understand fully why we sleep or how sleep helps us to recuperate and revitalise.
How much sleep do you really need ?
Source : National Sleep Foundation
The methodological breakthrough for the study of sleep came with the development of a technology to record brain wave activity in form of electroencephalogram (EEG). This provided an objective, ongoing measure of the way brain activity varied when people were awake or asleep.
Researchers know that individuals need different amounts of sleep, everyone sleeps at some time during day or night (Oster erg 1973). Sleep is a normal everyday behavior. About a third of our life will be spent sleeping, no matter how much we wish to extend the active, waking side. One reason we sleep each day can be found in the operation of our ‘biological clock’.
Electro-chemical theory contends that it is the level of caffeine in Raphe Nuclei that determines sleep. Sleep deprivation alters chemical composition of the zone i.e. level of caffeine falls below normal limits and we get sleep.
Sleep and its Stages
Three aspects of sleep help in understanding of sleep. These are –
Depth of Sleep.
Voluntary and involuntary control of sleep.
Depth of Sleep
Some people are readily around from sleep, others the deep sleepers are hard to awaken. Researches in sleep began in 1930s with the work of Loomis, Harvey and Hobart, but the work of Dement and Kleitman (1957) changed the course of dream research.
Dement and Kleitman designed sophisticated instruments for the measurement of the depth of sleep and determination of the occurrence of dreams. They were first to show and prove the existence of REM periods in sleep.
According to Dement and Kleitman sleep is all or none phenomena. We enter the sleep in a stepwise manner and sleep occurs in cyclic manner.
We know that there are two types of sleep –
REM or paradoxical sleep which usually occurs after Stage IV of NREM sleep.
NREM (Non Rapid Eye Involvement)
In all sleep involves Five Stages, Four Stages of depth (NREM) and Fifth Stage of REM sleep, in which dreams usually occur. Some people include Stage 0 which is a Pre Sleep Stage in the Sleep Stages but is not correct.
How Sleep Progresses
An individual as he prepares to go to sleep lays down and relaxes. He is now said to be Stage 0. In this stage a person shows high level of alpha waves. He is relaxed but awake 8 or 12. His frequency curves of brain waves (alpha) are evident in this stage.
This is also known as Light Sleep Stage. A person is easy to awake, body is more relaxed and these is a feeling of drowsiness. Brain waves becomes less regular and of reduced amplitude. With little or no alpha. There is complete absence of delta waves and spindles.
This also called an Intermediate Sleep Stage. It is characterized by appearance of spindles which are low voltage ‘rhythmical sequences’ of 13 – 16 cps. These waves that lasts for about one to two seconds.
This Deep Sleep Stage is marked by the presence of Delta Waves in significant proportion for the first time. The delta waves are high amplitude slow waves of 1 – 2 cps and it is estimated about 20 – 50 % of delta waves, interspersed with spindles is present in Stage III.
To be continued…