Since I became conscious of what dreaming was at the age of 3 or 4, I’ve been able to remember my dreams every day, almost without exception. While some dreams fade after a day or so, I can recall many of them months or years after.

I assumed everyone could as well until my senior year of high school, when we did a dream unit in psychology class. The teacher asked us to raise our hand if we could recall our dreams every morning when we woke up. In a class of over 20 students, I was one of only two people to raise their hand. I was shocked.

Up until then, I’d gone my whole life thinking everyone else remembered their dreams too. Turns out, that’s not the case for most people.

This made me begin to question, why was I able to remember my dreams while others couldn’t? Was this a good or bad thing? Did it mean I wasn’t sleeping well? These questions about dreaming remained years later, when I was well into my 20s. So I finally decided to investigate.

Let’s start with why and when dreaming occurs. Dreaming tends to take place during REM sleep, which can occur multiple times a night. This sleep stage is characterized by rapid eye movement (what REM stands for), increased bodily movement, and faster breathing.

Mike Kisch, co-founder and CEO of Beddr, a sleep tech start-up, tells Healthline that dreaming tends to occur during this time because our brain wave activity becomes more akin to that of when we’re awake. This stage usually begins about 90 minutes after you fall asleep, and can last for up to an hour toward the end of sleep.

“Whether they remember or not, all people do dream in their sleep. It is an essential function for the human brain, and also present in most species,” Dr. Alex Dimitriu, double board-certified in psychiatry and sleep medicine and founder of Menlo Park Psychiatry & Sleep Medicine, tells Healthline. So if everyone dreams, why don’t we all remember them?

That answer can vary depending on which theory of why humans dream you decide to follow, because there’s quite a few. Dream research is a wide and complex field, and dreaming can be hard to study in a laboratory. This is partly because the brain activity can’t tell us about the content of dreams, and you have to rely on subjective accounts from people.

“While some may suggest that dreams are a window to the subconscious, other theories posit that dreams are a nonsense result of the activity that takes place while we sleep and restore our brains,” Dr. Sujay Kansagra, Mattress Firm’s sleep health expert, tells Healthline. “And, if our need to dream is any indication of the brain participating in a restorative process, our inability to remember our dreams may simply be due to the sorting of essential and nonessential information during sleep.”

Basically, this theory suggests that dreams occur when our brain is processing information, eliminating the unnecessary stuff and moving important short-term memories into our long-term memory. So people who recall dreams may have a difference in their ability to memorize things in general.

Beyond that, a person’s brain may actually block out a dream so we don’t remember it the following day. “The dream activity can be so real and intense that our brains actually hide, or mask away the dream, so [it doesn’t] get lost between our waking experience, and our dream lives. Thus it is normal to forget dreams, most of the time.” Dimitriu says.

Ever had one of those dreams that are so realistic you aren’t sure if the events really happened? It’s really unsettling and strange, right? So in this case, our brain may help us forget so that we’re better able to tell the difference between our dream world and the real world.

On the flip side, brain activity can also allow someone to more easily remember their dream. “There’s a region in your brain called the temporoparietal junction, which processes information and emotions. This region can also put you in a state of intra-sleep wakefulness, which, in turn, allows your brain to encode and remember dreams better,” Julie Lambert, certified sleep expert, explains.

A study published in the journal Neuropsychopharmacology and reported by International Business Times suggested that those people who reported high dream recall had more activity in the temporoparietal junction than those who didn’t recall their dreams often.

Lambert tells Healthline that if someone consistently doesn’t get enough sleep, the amount of REM sleep they experience will drop, making it harder for them to remember their dreams the following day.

Even personality traits can be an indicator of whether someone will be able to remember their dreams.

Lambert continues: “Researchers also looked at the most common personality traits that are presented in people who can recall their dreams. Overall, such people are prone to daydreaming, creative thinking, and introspection. At the same time, those who are more practical and focused on what is outside themselves tend to have difficulty remembering their dreams.”

This may mean that some people are naturally more likely to recall their dreams than others, despite their quality of sleep.

Other factors, like stress or experiencing a trauma, can also cause people to have vivid dreams or nightmares that they’re more likely to recall the next day. For example, a person who’s coping with grief after losing a loved one may dream about the death in elaborate detail. Remembering the dream the next day may affect mood and cause even more stress or anxiety.

As a writer who’s constantly daydreaming and focused on introspection, this doesn’t surprise me. In fact, as I’ve grown, the way I view my dreams, itself, has evolved. For most of my childhood, I would watch myself in third person, almost like a movie. Then, one day, I started experiencing the dreams through my own eyes, and it never reverted.

Sometimes my dreams will build on each other, even expanding on a previous event’s dream in a current one. This could be a sign of my brain continuing its storytelling in my sleep.

While I was worried about my dreaming being a sign that I’m not sleeping well, it turns out dreaming itself doesn’t affect sleep quality. Though being able to remember dreams can sometimes be a sign of something else, such as a health condition or medication.

“While there may be some biological differences that result in some remembering dreams more than others, there are also some medical causes that should be considered. Alarm clocks, and irregular sleep schedules can result in abrupt waking during dream or REM sleep, and thus result in recall of dreams. Sleep apnea, alcohol, or anything that disturbs sleep can also cause dream recall,” Dimitriu says.

So the more you’re waking up throughout the night, the easier it may be to remember your dreams, at least in the short term. “In most cases, this happens because there’s something alerting that nudges us awake during dreaming, and in turn the dream content is recalled,” Dimitriu says.

What about those dreams that are so intense or disturbing that they literally wake you out of your sleep? You may find yourself in a sweaty panic, your heart racing, and sitting up in bed totally confused about what just happened. Dimitriu explains that having dreams or nightmares that regularly wake you up isn’t always normal and may be a sign that you need to speak to a doctor.

People who have post-traumatic stress syndrome (PTSD) may have vivid nightmares that involve flashbacks or replays of the trauma, either directly or symbolically. These can affect sleep quality and mood the next day.

Also, excessive fatigue during the daytime may be a sign of sleep issues that require a person to seek help. If at any point your dreams, or remembering your dreams, is causing you stress or anxiety, you should consider speaking with a doctor.

While researchers still aren’t sure what exactly causes dreaming, it’s a relief to know that remembering your dreams is a common, healthy thing. It doesn’t mean you aren’t sleeping well, and it definitely doesn’t mean you’re crazy or “not normal.”

Though I do feel more tired at times when waking up from a detailed dream, remembering them keeps things interesting — not to mention, it gives me some great story ideas. Aside from the time I dreamed about snakes for an entire week. That’s a tradeoff I’ll take.

Sarah Fielding is a New York City-based writer. Her writing has appeared in Bustle, Insider, Men’s Health, HuffPost, Nylon, and OZY where she covers social justice, mental health, health, travel, relationships, entertainment, fashion and food.