7 year old will make jerking movement and begin smacking lips during sleep. this happens at different times during sleep. eeg came back normal. cause?

Sleep myoclonus: Sleep myoclonus or "sleep jerks" usually occur in the rapid eye movement (REM) stage of sleep & can occur at any age from infancy through adulthood. When they are not part of a nervous system disorder, they are labeled essential or benign. This basically means they don't understand why they happen but are a variant of normal. Just notify your docs if anything changes.