sleep and its disturbance

8/13/2019 Sleep and Its Disturbance

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Sleep is defined as a regular, recurrent, easilyreversible state of an organism characterized byrelative quiescence and by a great increase in the

threshold of response to external stimuli.

(TURPIN 1986) Sleep is not a period of mere physiological

quiescence, but a complex phenomena which resultsfrom numerous different physiological processes.

(TURPIN 1986)


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Sleep is the physically inactive path of the circadiansleep wake activity cycle and is characterized bycyclical changes in the electroencephalogram (EEG)

and other physiological parameters.

The circadian sleep

wake

activity cycle refers totype of cyclical rhythm that regulates a variety ofphysiological functions.

The most familiar rhythm is the 24 hrs day nightcycle known as circadian or diurnal rhythm.

It is affected by the light and temperature.

It is influenced by work schedules and socialactivities.


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Sleep consists of five main stages.Four of non-rapid eye movement

sleep.

One of rapid eye movement sleep.

Movement between these stage isindicated by specific change on an

EEG. The five stages are :-


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The subject becomes drowsy and begins to fall asleep.The EEG shows alpha waves that are associated with the

waking state.

STAGE2

The subject is now asleep, although sleeping lightly .An unusual sound will disturb and arouse the subject

quite easily.Breathing is regular and slow.

The EEG shows the appearance of slow waves called K-complexesand bursts of rapid waves known as sleepspindles.

Stage 2 comprises 45-55% of total sleep time in youngadult .


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This is the beginning of slow waves sleep, which comprises 3-8% of totalsleep.

The subject is more deeply asleep and more difficult to arouse .

The EEG shows slow waves that became larger ,

known as delta waves .

STAGE 4

This is the stage of deepest sleep during which the subject is most difficult toarouse.

The EEG shows an increased no. of delta waves.

Sleepworking and enuresis occur during this stage of sleep, which comprises10-15% of the total sleep.


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This stage is characterized by rapid eyemovement .

The subject sleeps more lightly , with a change inthe EEG two waves more associated with

wakefulness.This is the stage of sleep where dreaming is

thought to occur.In many people this stage is characterized by

sleep paralysis, where they are unable to move.REM sleep comprises 20-25% of total sleep.


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When people prepare to fall asleep, they enter apresleep period in which they begins to feel drowsy .Once people fall asleep, a normal uninterrupted

nights sleep consists of 4-6 cycles. Each consisting of 4stages of NREM and a period of REM sleep .

The sleep cycle usually progresses from stage 1through stage 4 to 3 to 2 ending with a period of REM.The time spent in NREM and REM sleep changes as

the night progresses.During the 1sthalf of the night, NREM sleep

predominates, interspersed with REM episodes.

During the 2ndhalf of the night, NREM sleepdisappears, REM sleep predominates, interspersedwith short REM episodes.

Each sleep cycle lasts about 90 min during first half ofthe night and decreased to approx 60 min during the

2ndhalf of the night.


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The factors include - Illness

- Drugs

- Activity

- Diet

- Stress

- Environment


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Physical and psychological illness can causedisruptions in the sleep-wake cycle.

Certain illness can result in sleep disturbances.

( 2 )DURGS

Sedatives and hypnotics can affect sleep stagecycle and the sleep-wake cycle.

Its produce a more rapid sleep onset by reducingthe amount of sensory input to the RAS.


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Individuals who experience physical stressappear to require less total sleep time, havefewer episodes of light sleep and have fewer

interruptions in all stages of sleep. When an individual experiences psychological

stress, the amount of sleep and total sleep timeappear to increase .

High levels of anxiety produce disruptions inthe sleepwake cycle by activating the RAS andpreventing the onset of sleep.


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It is a critical component in initiating the sleepcycle.

The environment and environment clues are

often part of an individuals sleep rituals thatpromote sleep onset and sleep efficiency.

Alteration in the environment often disrupt theinitiation and maintenance of the sleep cycle.


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Exercise associated with moderate fatiqueenhances sleep.

sleep and its disturbance

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