Dreaming is just really weird, when you think about it.

When you're asleep, your brain makes up these elaborate scenarios where you're leading a herd of talking apples or riding robot llamas through the jungle or something. And most of the time, you have no idea it isn't real.

Then when you wake up, you forget most of the dream and move on with your life. Like, that's not strange at all. There's a lot of research into the science of dreaming, and sleep in general, but dreams can be especially important in psychology.

I mean, don't go reaching for those dream interpretation books or anything. But your dreams might mean more than you think. [intro]. Even though everyone probably does it, scientists still aren't sure exactly how we dream.

It's often associated with rapid eye movement, or REM sleep, a phase of sleep where your brain looks as active as when you're awake, but there's evidence that we dream in non-REM sleep, too. So we're still figuring out some of the biology involved, but psychologists do have a few theories about how our brains use dreams. And sorry, Sigmund Freud, but they aren't all freaky sex messages.

In fact, a lot of our dreams are pretty boring, and according to one theory, that's because your brain uses dreams for learning and memory consolidation in a process called cognitive-level memory reactivation. The idea is that, while you dream, your brain reactivates the neurons it used to learn information while you were awake. These kinds of dreams usually happen during non-REM sleep in the beginning of the night.

For example, in a 2010 study published in Current Biology, participants practiced completing a virtual maze, then either took a 90-minute nap or stayed awake. During the next round of testing, those who took a nap finished faster on average than those who didn't, but the real MVPs were the group who took a nap and dreamed about something related to the task: They improved up to ten times more than the others. This doesn't necessarily mean that dreaming itself gives you a better memory.

The dreams might just be a side effect of what your brain is doing — reactivating neurons to solidify information and encode it into long-term memory. But it might explain the more boring dreams we have. It doesn't really explain why some of our dreams are just flat-out weird, though.

And that's where the contemporary theory of dreaming comes in. The idea is that your dreams are mainly controlled by what emotions you're feeling, not what you've learned lately. If you're experiencing one really strong emotion, you'll probably have simpler dreams — like, if you're feeling overwhelmed, you might dream you're being sucked up by a tornado.

But if you're feeling multiple emotions, your dreams can get more complicated and random. This theory may also help explain the relationship psychologists have seen between dreaming and trauma, especially in those with post-traumatic stress disorder, or PTSD. Frequent, disruptive nightmares are actually one of the potential criteria for diagnosing someone with PTSD, with up to 96% of patients reporting nightmares related to the trauma they experienced.

According to the contemporary theory of dreaming, people with PTSD have nightmares because dreaming can help us resolve traumatic emotions. By processing them in our sleep, the memories might feel less painful when we're awake. That's what the brain is trying to do, at least.

It's not always successful, which is why PTSD often doesn't just go away on its own. There's also another theory, the threat simulation theory of dreaming, which says that nightmares could be your brain preparing you for danger in the real world. According to threat simulation theory, dreams were selected for during evolution to help us survive — as opposed to being controlled by emotions.

So if you dream you're being chased by an angry sabre tooth tiger your brain might just be preparing you in case you're attacked in real life. The idea matches what psychologists have seen in studies — like in a 2005 study of almost 200 children, where researchers found evidence that being exposed to danger, like violence or abuse, primes our brains to dream about dangerous scenarios even more, possibly to prepare against future threats. And based on what we know about dreaming and trauma, it makes sense that your brain would do this.

I mean, dreaming is kind of like a simulator where you can't hurt yourself. The threat simulation theory alone can't really explain all of our dreams, though, and it's possible that your brain uses dreaming in a lot of different ways. There are also plenty of scientists who think dreams don't have a specific purpose at all — they're just what happens when neurons randomly fire while you sleep.

So, it's hard to know exactly why you dreamed that you forgot to study for a final and showed up without pants, or tried to ride a horse down the highway. But your brain might be trying to help you process emotions or prepare for some kind of threat. Thanks for watching this episode of SciShow Psych, brought to you by our patrons on Patreon.

If you'd like to help us keep supporting the show, you can go to patreon.com/scishow, and for more episodes like this, visit youtube.com/scishowpsych and subscribe.