Sleep and Its Mechanism

Abstract

Sleep is an integral part of our daily life. We spend
one third of our lives sleeping. Sleep is also an
insistent drive. People will drift into sleep, even if
they are in a situation (for example, driving a car) in
which sleeping will mean their death. It is a period
of physical inactivity during which there is
unconsciousness from which the person can be
aroused by sensory or other stimuli. The loss of
consciousness during coma, surgical anesthesia and
epilepsy is not considered as sleep. Sleeping people
are not consciously aware of the external world but
they do have inward conscious experiences such as
dreams. Furthermore they can be aroused by
external stimuli such as alarm of the clock or cry of a
child. Requirement of sleep varies with age and also
in individuals. Infants sleep for more than 18 hours
while young children for 12 hours. Adults require 6-8
hours sleep, while elders sleep less.
Sleep is an active process consisting of alternate
periods of two types of sleep. During a night, every
body enjoys two types of sleep; slow wave or nonREM sleep and REM (Rapid Eye Movement) or
paradoxical sleep. Depth of sleep varies from very
light sleep to very deep sleep.