Sleep : its physiology and pathology

Abstract

Sleep as Oswald put it "is a recurrent, healthy condition of inertia and unresponsiveness associated with various physiological changes"; so much so that the knee-jerk disappears (though some superficial reflexes remain), urine secretion decreases, stomach secretion is reduced (in spite of increased hunger contractions), heart rate slows down (due to general body inactivity) and the blood pressure falls. The B.M.R., oxygen saturation and rate of respiration all tend to decline, so that there is a general reduction of activity. Yet recent findings about sleep indicate that it is not merely an inactivation but a different sort of vigilance and activity. The REM state of sleep alone, is considered on the basis of certain biochemical evidence as an active state controlled at the level of the brain stem and marked by increased cerebral metabolism. Despite a seemingly sophisticated arrangement to ensure motor paralysis through the reduction of tonic and spinal reflexes in sleep there is during the REM phase an outbreak of diffuse motor-impulses within the central nervous system.