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.
There were two forms of education in ancient Greece: formal and informal. Formal education was attained through attendance to a public school or was provided by a hired tutor. Informal education was provided by an unpaid teacher, and occurred in a non-public setting.