Why do we dream?

During Rapid Eye Movement (REM) sleep — which occupies about 20–25% of a full night — the brain becomes nearly as active as when awake while the body is temporarily paralyzed. Leading theories suggest dreams help consolidate short-term memories into long-term storage, emotionally regulate stressful experiences, and run "threat simulations" to prepare us for real-world dangers. The average person has 3–5 dream episodes per night, totaling roughly two hours. Yet 95% of dream content is forgotten within five minutes of waking, likely because the prefrontal cortex (responsible for memory encoding) is less active during REM.