You are running through the woods and a bear is chasing you, when all of a sudden you wake up in your bed and realize it was just a scary dream. Our nightmares can sometimes feel super scary, even if what’s happening isn’t real.
Fear is a natural part of being a human. In fact, you may have even felt shaky or sweaty after waking up from a bad dream. It’s all part of something we call the fight or flight response.
When humans are faced with something scary, this response helps them decide if they should face their fears and fight or run away by taking flight. This fight or flight response works even when you are asleep.
When humans fall asleep, they cycle through different phases of sleep. During one of these phases, called Rapid Eye Movement (REM) sleep, their eyes are moving rapidly under their eyelids, the brain is very active, and most people report dreaming. This type of sleep first happens about an hour and a half after you fall asleep and then again every 90 minutes or so throughout the night.
That’s what I found out from my friend Willie Vanderheyden, a researcher at Washington State University who studies sleep. He’s curious about the types of things that can disturb our sleep, too.
He told me that the real answer to your question is that we don’t know exactly why we have nightmares, or dreams, for that matter. After all, it’s hard for someone to be dreaming and report what they are dreaming at the same time. But scientists have a few ideas.
We may get nightmares after we’ve experienced something that made us afraid. For example, watching a scary movie before bed or seeing something scary happen during the day.
We may also get nightmares because of something coming up that makes us anxious. For example, we might be giving a big speech at school. Nightmares may be a way for us to process the day, prepare us for something in the future, or help us look at problems in our lives from different angles.
People have different fears, so they have different types of nightmares. Maybe you had nightmares about monsters or imaginary creatures when you were little. But maybe as you grow up, they are about more real fears like heights or natural disasters.
Vanderheyden told me it’s actually pretty common for kids to get nightmares. They sometimes get them even more than adults do. But we still don’t really know why that is.
“Sleep is something that everyone does, but we still don’t know why,” Vanderheyden said. “Everyone thinks we have it very figured out. But we actually know very little about it.”
That’s part of the reason he is so curious to learn more about how sleep works. Who knows, maybe one day you can help us learn more about nightmares and why we get them, too. Until then, keep dreaming up great questions.