sleep.docx - 1 PRE MID ASSIGNMENT NO 2 TOPIC PHYSIOLOGICAL...

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PRE MID ASSIGNMENT NO 2
TOPIC: PHYSIOLOGICAL AND BEHAVIORAL DISCRIPTION OF SLEEP
NAME: SYEDA NUSHRAH NOOR
MAJOR: APPLIED PSYCHOLOGY
COURSE TITLE: NEUROPSYCHOLOGY
COURSE CODE: APSY305
SECTION: B
SEMESTER: 3
SUBMITTED TO: MISS SONIA NAEEM
DATE OF SUBMISSION: 1
st
October, 2018
SESSION: 2017-2021
KINNAIRD COLLEGE FOR WOMEN, LAHORE

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INTRODUCTION:
Sleep is defined as a state of perceptual disengagement from and unresponsiveness to the
environment, by a behavioral point of view. However, until 1950s people thought sleep to be a
flaccid and dormant part of our daily lives, and an intermediate state between wakefulness and
death. But now, with advancement of knowledge, we know that brain is in fact, very much active
during sleep.
ANATOMY OF SLEEP
SLEEP CYCLE:
A Sleep cycle is approximately 90 minutes long and it refers to the period in which individual
progress through the stage of sleep discussed below. On average humans go through around four
to five sleep cycle every night. However an individual does not go to REM sleep directly from
deep sleep. Rather there is a transition from light to deep sleep as the cycle progress. And then a
reverse transition from deep to light sleep occur ending with REM sleep. The cycle repeats over
the night. The order of the sleep cycle looks something like this:
Light sleep (stage 1)  Light sleep (stage 2)  Deep sleep (stage 3&4)  light sleep (stage
2)  light sleep (stage 1)  REM sleep.
As the night progress we spend more time in REM sleep as compared to earlier 2-3 sleep cycles
that incudes longer NERM stages
(“
Stages of Sleep and Sleep cycle”, 2018).
STAGES OF SLEEP:
Sleep is a complex process involving both physiological and psychological processes. There are
two distinct states exist between sleep i.e. Non rapid eye movement (NREM) and rapid eye
movement (REM). Each of this stage is involved in its own neural activity and brain waves.
NERM sleep:
During NERM sleep, rain waves recorded on EEG are typically slow and high voltage. Non
rapid eye movement is further divided into four stages which are explained below:

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Stage 1:
Stage 1 is typically 1- 7 minutes long and it’s the initial stage of sleep where an individual’s sleep
can easily be discontinued if the person is being called softly or touched lightly etc. For
Example: a person may experience a sudden muscle contraction proceeded by sensation of
falling, in this stage (Carskadon and Dement, 2005).
Therefore this stage is being associated with low arousal threshold. Stage 1 occurs as a
transitional stage throughout the night in addition to being just an initial wake to sleep transition
stage. For this reason, an increase in the amount and percentage of stage 1 indicates the severely
disrupted sleep.
Stage 2:
Stage 2 continues for about 10 to 15 minutes. In this stage eye movement stops and brain waves
slow down with occasional outburst of brain waves known as sleep spindles and K- complex .