Sometimes people find themselves unable to move their postural muscles immediately after awakening. Why?
A) Blood pressure is too low.
B) The motor nerves are inactive until body temperature reaches its normal level.
C) An increase in light striking the eyes reflexively inhibits the motor neurons.
D) Part of the brain is still asleep.

Question

Quizplus · Accepted Answer

During sleep, the brainstem sends a signal to inhibit muscle movement to prevent acting out dreams. When a person wakes up, the brainstem needs time to reactivate the muscle movement signal, which can cause temporary muscle weakness or paralysis (sleep paralysis). This is also why some people experience sleep paralysis when falling asleep or waking up.

Sometimes People Find Themselves Unable to Move Their Postural Muscles