Question

paraphrase this paragraph

There are numerous brain centers, pathways and neurochemicals controlling sleep, but these tell us little about the purpose of sleep - merely how it is regulated. Most of us have been without sleep on some occasion, and have experienced impairments to thinking and behavior. One reason why sleep is so critical to efficient cerebral function is because this part of the brain cannot really rest and recover during wakefulness. Even when we lie relaxed but awake on a bed, with eyes shut and the mind cleared of all thoughts, cerebral activity and cerebral metabolism remain unchanged - in a state of ‘quiet readiness', ready to react. If the cortex periodically requires reduced sensory input and some disengagement from reality, then only sleep (particularly deep non-REM sleep) can provide it. This is probably why the obvious effects of human sleep deprivation are behavioral.

Answer 1

The brain is always active even when we are resting with eyes closed. Only when we are in a deep sleep when there is no rapid eye movement, the brain gets much required rest. If we are deprived of sleep, the brain is devoid of rest and it results in impairment of thinking and alteration in behavior.