While falling asleep or waking up, your brain helps the muscles in your arms and legs relax. With sleep paralysis, you regain awareness but can't move. Paralysis is temporary and isn't a sign of major medical issue. Pinpointing the source of your symptoms and addressing them can help you avoid future episodes.
During a sleep paralysis episode you're aware of your surroundings but cannot move or speak. But you can still move your eyes and breathe. Many people hear or see things that aren't there( hallucinations) making episodes more frightening.