Question

"Sleep is a state of unconsciousness." Substantiate the statement.

Answer 1

Sleep: It is a state of unconscious need from which a person can be aroused by appropriate sensory or other stimuli. Sleep is of two types, Slow-wave sleep and REM sleep.
1. Slow-wave sleep: The brain waves are very slow. This sleep is called as "dreamless sleep." Dream actually occur very often and even nightmares occur. This sleep usually decreases the blood pressure, respiratory rate and BMR.
2. REM (Rapid Eye Movement Sleep): REM lasting 5-30 minutes usually appear on an average of every 90 minutes. It is usually associated with active dreaming. The muscle tone throughout the body is exceedingly depressed during this sleep indicating strong inhibition of the spinal projections from the reticular formation of the brainstem. During this sleep, the heart rate and respiration usually become irregular, the brain is quite active. But, the brain activity is not channelled in the proper direction for persons to be aware of their surroundings and therefore be awake. Sleep restores both sensitivities of nervous system & balance among the different parts of CNS. Due to good sleep arterial blood pressure fails, pulse rate decreases, skin vessels dilate, muscles fall into relaxed state & overall metabolic rate of the body falls 10 - 30%.