You're being chased by a shadowy creature. You can’t get a good look at it, but it’s terrifying—and out to get you. The next minute, you’re falling through the sky. But just before you hit the ground with a SPLAT, you jerk awake. Thank goodness: It was just a nightmare!
Your body doesn’t completely shut down when you sleep. As you rest, your brain is still hard at work, making connections, cataloguing information, and storing memories from the day. The result of all that activity is dreams. “Dreams are our brain thinking in a very different state,” says Deirdre Barrett, a psychologist at Harvard Medical School in Massachusetts. “During sleep, the areas of the brain associated with imagination, emotions, and storytelling are turned up high, while our logic is turned way down."