People dream because it likely serves several important functions related to mental, emotional, and physical health. Major theories about why we dream include:

• Dreaming helps process and consolidate memories from the day, deciding what information to keep and what to discard.
• Dreams support emotional processing, helping people work through daily feelings, reduce tension, and potentially improve mood and mental well-being.
• Dreams may aid problem-solving and creativity by allowing the unconscious mind to explore scenarios and ideas without daytime constraints.
• Some theories propose dreams function as mental "housekeeping," clearing unnecessary information or acting as distorted replays of recent events.
• Dreams might also serve as a rehearsal mechanism for challenges or threats, preparing the brain for real-life situations.
• While some researchers believe dreams have essential purposes, others suggest dreams may be incidental brain activity during sleep.

Dreaming mostly occurs during rapid eye movement (REM) sleep when the brain is highly active, and most people dream multiple times per night even if they don't remember their dreams upon waking.