When you think back on your most vivid memories, there are some obvious biggies that probably stick out, like, say, your graduation day and when you got married. But not all strongly remembered memories are ones you’d necessarily classify as positive. For instance, maybe you got in a car accident, and you find reminders of tough to shake. Well, according to recent research, there’s a reason why you can likely remember scary memories in particular.

In fact, most people have scary memories they can recall vividly, says Tracey Shors, PhD, a professor of behavioral and systems neuroscience at Rutgers University and author of Everyday Trauma. A recent study published in the journal Nature Communications found that the stress neurotransmitter norepinephrine (aka noradrenaline) facilitates fear processing in the brain by stimulating certain nerve cells in your amygdala (the part of your brain responsible for emotions, emotional behavior, and motivation) to create a repetitive bursting pattern of electrical discharges.

That pattern changes the frequency of brain waves in your amygdala from a resting state to an aroused state. And that promotes the formation of fear memories. Basically, when you’re scared, your body releases a flood of stress hormones that essentially sear the memory into your brain.

The scary memories “stick with us so that we can remember them and then use the information to avoid similar experiences in the future.” —Tracey Shors, PhD, behavioral scientist

This doesn’t happen solely to torture you down the road, though. The scary memories “stick with us so that we can remember them and then use the information to avoid similar experiences in the future,” Dr. Shors says. “It’s meant to train us to prepare ourselves for future bad events.”

Jason Moser, PhD, a neuroscience professor at Michigan State University, agrees. “Scary experiences are usually very evolutionarily and motivationally important—matters of life and death—and so our cognitive system tries to lay those memory traces down strongly for learning over time, to avoid situations that might harm us,” he says.

Other life events and emotions that can cause this reaction

Unlike the car accident you might’ve been in, you probably don’t remember what you had for lunch on the third day of seventh grade, and there’s a reason for that: Your brain just doesn’t think it was that important. But, for life moments that were important to you, you can get a similar norepinephrine release, Dr. Shors says. “Norepinephrine is the neurotransmitter that’s released in response to almost anything that’s arousing… You would have a release of norepinephrine if you were really happy, like when you get married.”

Again, this happens in response to stimuli that you really need to pay attention to, because your brain is just trying to help you stay safe. “What cognitive science and neuroscience have taught us is that the more evolutionarily and motivationally important an experience is—life and death or life-defining, like having a child—the more likely we are to remember them,” Dr. Moser says.

How to make sure scary memories don’t take up outsize brain space

Dr. Moser says there are “lots of strategies” you can try on your own or with the help of a mental-health professional to ensure scary memories don’t rule the roost of your brain. “Distraction can be useful sometimes, so long as it doesn’t become the only technique the person uses,” he says. Meaning, you could try to distract yourself with thoughts of something else if you want to change your thoughts away from a scary memory. But, do know that “if distraction is used over and over, it could actually lead to avoidance of important thoughts and feelings that could keep the memories alive for a long time,” he adds.

Instead, mental-health professionals typically recommend that you “review the scary memory for important information that you can effectively reflect on and grow from,” Dr. Moser says. This can be something that you do on your own or by talking it out with a close friend, family member, or professional. “Maintaining a balance between distraction in the moment—like when we have to get important things done during the day—and approaching the memories to gain new insights is really critical to long-term well-being,” Dr. Moser adds. Other strategies he recommends include exposure to nature, exercise, and yoga can help “as long as you continue to try and balance your approach to understanding the experience.”

If thinking about a scary memory again seems, well, scary, Dr. Shors recommends keeping this in mind: “Every time you bring a memory back to the present from the past, you make another memory, and you bring back the memory in a safe context. Then, the brain learns that memory doesn’t necessarily need to be associated with fear now.”

And, of course, if you’re struggling with a scary memory or feel that it’s keeping you from going about your daily life, Dr. Moser says it’s time to talk to a mental-health professional.