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Dreams are like a forest walkway: there’s no clear sense of direction and you can easily get lost. ollierb/flickr, CC BY-NC-ND

Curious Kids: Why do our brains freak us out with scary dreams?

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

Why do our brains freak us out with scary dreams? – Niamh, 8, Newcastle.

Great question, Niamh.

Getting a fright from a dream is very normal. But our brains don’t have a secret plan to freak us out with nightmares.

In the olden days, many people believed dreams were a window to another world. People lived two inseparable lives: one in a waking world and the other in a dream world.

They believed the dream world contained a mixture of the past and the future, gods and goddesses, and helped people find purpose with their lives. These dreams often revealed new people and ideas, which explains why some people found them scary. Others saw them as a sign or a prophesy from the gods.

The dreamcatcher is a Native American invention used to protect people while they sleep. bsheets/flickr, CC BY-NC

When scientists first studied dreams, around 200 years ago, they thought dreams were a special type of story that brains told themselves. Scientists thought it was a special language where ideas and emotions were explained using symbols and signs. Different parts of the brain would talk with other parts in this dream state.

If your house was damaged, for example, it was supposed to represent the dreamer, and the brain was trying to tell you that you or your ego had been damaged. Dr Sigmund Freud, seen by many as the founder of psychoanalysis, wrote a very famous book about dreams called “The Interpretation of Dreams” in 1900.

Sigmund Freud wrote a very famous book about dreams called The Interpretation of Dreams. Wikimedia

About 100 years ago, people started to explain things more thoroughly using science and technology. This brought a different way of understanding why things happen. But it doesn’t mean the way other people thought about dreams was necessarily wrong.

There are two main types of sleep, according to scientists, and dreams occur during a stage called REM sleep (Rapid Eye Movement).

REM sleep is when we are most likely to dream. It is called REM because people quickly flick their eyes back and forward while they sleep.

If you watch cats or dogs sleeping, you will sometimes see their eyes moving and their paws twitching. This indicates they are in REM sleep and probably dreaming. But we don’t really know what cats and dogs dream about because they can’t tell us.

The other main type of sleep is non-REM sleep, called deep sleep or Slow Wave Sleep (SWS). In this type, people sleep very deeply. But they don’t typically report dreaming. If you try to wake them, they’re often slow and confused.

For the last 50 years, some scientists believed that dreaming was the way brains decide what to keep and what to throw away each day. In a sense, it’s like cleaning your room: your brain decides what you’ll need to know and tosses the unimportant stuff into the bin.

Scientists think young people find it harder to separate the waking and dreaming worlds and often confuse the two.

Filmmakers have taken this confusion to the screen again and again over the years. There are many movies about how dreams can scare and confuse us.

As you can see, lots of people wonder why dreams are scary. The truth is that we don’t know for sure.

What we do know is that all people dream, and all people think dreams can be weird, scary and puzzling at times. We share the ability to dream with all warm-blooded animals, so it likely has an important function in keeping us healthy.

I suspect everyone tries to make sense of their dreams — even scientists. But we still can’t see inside someone else’s brain to see what they are dreaming about. And that’s probably a good thing.

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