The primary medical name for the phenomenon where you wake up but are unable to move because your muscles are still in a state of sleep paralysis is sleep paralysis
Sleep paralysis is a temporary inability to move or speak while falling asleep or waking up, often accompanied by vivid, frightening hallucinations and chest pressure. Occurring during the transition in or out of REM sleep, it happens when the brain wakes up but the body remains in a paralyzed state. It is usually harmless and lasts for seconds to minutes.