You're running, but you're not going anywhere. You're falling, but you never hit the ground. You're watching your loved one waste away, but there's nothing you can do about it.

If you're like most people, then you might be covered in a cold sweat by now, recalling a nightmare.

Though our dreams are highly personal, and often based on what happened to us over our lifetime and during our day, there are some themes that unite us all.

"These dreams are related to issues that every person has in their waking lives," Michael Schredl, head of the sleep lab at the Central Institute of Mental Health, Mannheim, Germany, told Insider.

It's tough to make generalizations about nightmares, since science hasn't agreed on why we even dream in the first place.

But there are basic patterns in nightmare themes that may help you translate what your brain is trying to express, Schredl said. Understanding these patterns could be a starting point to identify what emotions you're dealing with in your subconscious.

In a 2018 study, Schredl and his colleague analyzed over 1,200 nightmares, from asking participants to recall their most recent distressing dream. They then categorized them into common themes.

Here are the top 10 they found.

10. Infestation

Having an infestation in your home makes reality feel like a nightmare. So dreaming about an invasion of creepy crawlers or fuzzy fiends could be a literal fear or a symbolic one.

If it's symbolic, an infestation could represent a fear of disease or dirt, or any other things you personally associate with mice, roaches, or rats, Schredl said. Since there are many ways these dreams can unfold, there are many ways they can be interpreted.

It could also be an example of feeling insecure or unsafe in your home, Schredl said.

9. Evil presence

In the ninth spot, there's the eerie feeling of suspecting that there may be a ghost, demon, or alien nearby. This could mean that the dreamer sees the offending presence, or merely that they suspect one is near.

These sorts of sleep hallucinations often plague people suffering from sleep paralysis, according to the Cleveland Clinic. This unsettling sleep disorder occurs when the parts of the brain that keep you still during sleep and the parts that keep you sleeping miscommunicate.

In this state, people often report a ghoul standing over them as they struggle to move. Talk about not getting your beauty sleep.

These horror-movie characters are likely your brain using familiar cultural symbols to depict your fear in the moment, Baland Jalal, a neuroscientist at Harvard, told the Guardian.

Imagine, "you've grown up being told by your grandmother that spirits and demons inhabit your village after dark. You wake up during REM sleep, you see some kind of a shadow, and you starting panicking, creating more body image hallucinations which your mind interprets in this cultural narrative and so you perceive a demon coming towards you," he said.

8. Catastrophe

Fires, floods, nuclear fallout — a common subject of many people's dreams is anything that could be mistaken for the end of times. Disasters ranked at number eight in the survey, found in about 4.5% of the dream reports Shredl studied.

These could signal general apprehension for the future, as a way for your brain to ruminate on something you're worried may occur, according to Stanford's Corelli. It depends on whether you view the changes coming into your life as positive or negative.

Or, if you've experienced a natural disaster, it could be your mind working its way through the situation as a way of processing your trauma, according to researchers from the University of Buffalo.

7. Feeling worried

Do you know the feeling when you're sure you've forgotten something important, something big, but you're not sure what it is?

Many people dream about this feeling, with apprehension and worry ranking as the seventh most common nightmare.

People in Shredl's study reported feeling like they knew something was wrong, but they didn't know what, and that made them more uncomfortable.

Fear of the unknown seems to be something that many of us share, even in our dreams.

6. Disagreements

Interpersonal conflicts come in as the sixth most common. In these scenarios, the dreamer has or witnesses a non-physical fight.

These dreams could be emblematic of some social anxiety you have about a personal relationship, according to Psychology Today. You could be dreading a conversation you need to have or processing a conflict that has already happened.

5. Sickness and death

Health-related concerns and death ranked right in the middle of the survey and was found in 11.6% of reports.

In these types of nightmares, the dreamer reported watching themselves or a loved one become sick, suffer through a disease, or die.

These dreams are complex, and could represent many things depending on what you're personally going through.

They could be emblematic of a general fear of sickness and death or feeling out of control of your personal well-being, Insider previously reported.

It might also be a way for you to process grief, according to a 2020 study.

4. Being chased

In these dreams, you might be being pursued by a human, an evil presence, or something you can't even see.

Schredl explains how the basic patterns of a chase dream can tell you what it means. In a nightmare like this, you're afraid as you run from something that you feel is getting increasingly close to you.

Experiencing fear and running away from what causes it is psychology 101. This is avoidance behavior, Schredl said. So generally, dreams about being chased usually mean you're anxious about something you may be avoiding.

3. Accidents

This broad category of dreams includes themes like falling, car wrecks, drowning, and more. Shredl found this theme in 15% of reports.

But when broken down by sex, males reported significantly more falling dreams than their female counterparts.

These dreams might be more literal than you might think, representing a fear of heights, driving, or the ocean. But they could also represent feeling out of control, fearing death, or feeling helpless, Schredl told Insider.

He explained these dreams by comparing our brains to a movie director.

"If you're a film director, and you have to depict the situation of the feeling of completely helpless, a falling dream, the falling situation, might be one of those. Because in the falling dream the only thing you know, you know, is that you will fall down and be dead," he said.

So these sorts of accident dreams can be our brain's way of dramatically expressing how we're feeling about our own mortality, capability, or health.

2. Physical aggression

Taking number six on the list — disagreements — a bit further, you arrive at the second most common dream, which is physical aggression.

In these scenarios, the dreamer may be attacked, participate in a fight, or witness other people duking it out.

This type of nightmare may reflect social anxiety, a literal fear of violence, or concerns about being vulnerable to other people's criticisms, Insider previously reported.

1. Failure

Coming in at number one is the broad category of failure and helplessness, which Schredl documented in 18% of reports.

This encompasses everything from failing to achieve a goal, to being late, lost, unable to speak, losing or forgetting something, or making a mistake.

This includes the all too stereotypical dream of failing a test, which made up 3% of all nightmares reported in the study.

Since this is a broad category, there are many different interpretations you could make. Exam dreams might mean you're insecure about your ability to perform at work or home, or remembering a certain troubling event, Schredl said.

Looking back at the pattern of all these dreams gives us a clue. For example, in a nightmare about an exam, it goes something like this:

"Someone else is looking, how do you perform? Do you know the stuff you have to know? And of course, this is a typical situation, for I think every person who is working," Schredl said.

So if you're dreaming about these scenarios, you may be feeling a little insecure about your own abilities, or how other people think about your performance.

This article was originally published by Business Insider.

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