Startle

Sleep is a physiological phenomenon that the brain's advanced nervous system produces universal inhibition, and it is a process from shallow to deep. When a person just fell asleep, he was in a lighter state of sleep, that is, a hazy state. Some of the nerve cells in the cerebral cortex have been inhibited, and some have not been completely inhibited. At this time, some excitement information existing inside and outside the body can interfere with the inhibition of the cerebral cortex and produce nerve reflexes that cannot be controlled; if this nerve reflex occurs in the motor nerve, causing local muscle contraction in the limbs, hand and foot arrest will occur suddenly This is the startle in sleep.