Sleep paralysis occurs as a person is moving into or out of REM (rapid eye movement) sleep, the deepest part of sleep. During REM sleep, the body is largely disconnected from the brain, effectively leaving the body paralyzed.
England and a few other countries start formal education at age 4 or 5. That's harmful and misguided.
The Formal Operational stage [ 3 ] is the final stage in Piaget's theory. It begins at approximately 11 to 12 years of age, and continues throughout adulthood, although Piaget does point out that some people may never reach this stage of cognitive development.