Love dissecting your dreams? Here's why our brains create stories in our sleep.

You're back in school and suddenly have to take a test, despite not having been present to learn any of the material. Your teeth are suddenly falling out. You run into an acquaintance you haven't seen in 20 years. You're suddenly falling from a high distance, or maybe even flying.

Dreams are a concept that humans have been fascinated with deciphering for thousands of years. Experts are still working on determining exactly what causes them, but they have posited a number of theories that range from spiritual to neurological as to why our brains decide to tell us stories when we fall asleep.

"There is something poetic and mysterious about dreaming," says sleep science advisor Carleara Weiss, PhD, MS, RN. "It feels like the brain is hosting a Netflix show made from our subconscious mind."

If you're searching for greater meaning in your dreams, here's what sleep scientists want you to know about dream content and how it relates to quality of sleep.

Why do we dream?

Dream theories date very far back in history, from Hippocrates theorizing that dreams can predict disease to Sigmund Freud viewing dreams as windows into "conflicting impulses that are rejected from waking consciousness" to Carl Jung suggesting that dreams help to problem-solve real life conflicts, according to the American Psychological Association (APA).

Depending on your cultural background, you may have a wide variety of beliefs about how the content of your dreams reflects your living reality. From a spiritual perspective, some believe that dreams are "premonitory, a form of communication to/from the afterlife, another dimension or deceased loved ones," for example, Weiss notes.

From a scientific perspective, experts don't yet have a definitive answer to the question of why we dream, but they believe it has to do with processing emotion and consolidating memories, Weiss says. In the 1950s, researchers discovered the concept of REM sleep, which is when most dreams take place. (It's also a period that aids in mood regulation, brain development and emotional regulation, according to Harvard Health.) That's when the concept of dreaming as a neurocognitive process first came about, per the APA.

"There is also some evidence that dreams can aid in problem-solving and creativity, serving as a mental housekeeping process that reviews the experiences of the day, discards unnecessary memories and stimulates the brain with various scenarios," she adds.

Other theories, per the APA, that some sleep researchers posit, is that nightmares serve as a safe place to work out a person's fears or worst-case scenarios, or even a way to show someone a horrible scene so that they're less likely to be upset by a similar one while awake.

Does dreaming mean good sleep?

Dreaming in and of itself isn't a definitive indicator of good sleep, Weiss says, though she notes the two aren't entirely separate concepts.

"Because most dreams happen during REM sleep, it can be inferred that the person dreaming is reaching the REM sleep stage," she says. "This stage also involves intense brain activity, which is essential for memory consolidation, all of which is good for sleep and wellbeing."

Experts have also discovered that people may report feeling as though they got better sleep after experiencing vivid dreams, while less in-depth dreams and nightmares can leave them anecdotally reporting that their sleep quality was lower, according to the Sleep Foundation.