During your latest shut-eye adventures, you chopped the head off of a six-legged rabbit while wearing a neon pink bonnet and screaming, "Gesundheit" at the top of your lungs. You aren't sure whether that dream means something, unless it's that perhaps you consumed too many hallucinogens during college, or merely ate some bad carrots yesterday.
Scientists and sleep experts know when people normally dream. Typically, you dream during the rapid-eye movement(REM) portion of the sleep cycle. You can see when a person (or even your cat or dog) is experiencing REM sleep because their eyes zip to and fro and their bodies may twitch and jerk, too. The brain's electrical patterns are very active in this phase, just like when you're awake.
But researchers don't really know WHY you dream. It may be a way of reflecting on or releasing the stress of everyday life, or even an unconscious way of helping you unravel challenging experiences. It could be a way that your mind protects itself from threatens and dangers.
It could be a biochemical way for your brain to sort, file or store short- or long-term information. Perhaps dreams are a way to reconcile your past and present experiences to prepare and steel you for the future.
Regardless of their purpose, dreams are a cornerstone of the human experience. They entertain and haunt us and serve as reminders that our inner world is just as deep and strange as the exterior world all around us.