The Science Behind Your Very Worst Dreams
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The Science Behind Your Very Worst Dreams

Nightmares may have evolutionary origins.

For Sky Sutton, the insomnia and nightmares showed up right after Election Day. "The night that Trump was elected, I had this dream that my whole town was running away from him," she says. "I never saw him, but we all knew he was coming. Where I live is a very liberal, queer-friendly area, so he was out to punish us. We had to escape, all my neighbors and friends and family. There were hundreds of us, and we were all running."


When she jolted awake, mind racing, heart nearly pounding out of her chest, she threw up. Since then, she's had about three Trump-related nightmares a week, and though not all of them result in purging, many are hard to let go of. "I had one last week that was a ten out of ten," she recalls. "My home was invaded with dark, faceless figures and I had to fight to get them out. Wrecked my whole day trying to shake it off."

Like Sutton, many Americans are grappling with the reality that Donald Trump is indeed the leader of the free world—and the battered psyches are evident. According to the American Psychological Association, in January, stress levels in the US saw the first statistically significant increase since 2007, and bad dreams like Sutton's aren't unheard of: Back in November, Slate chronicled the election-related nightmares of their staff and last week, a slew of individuals confessed their Trump-induced nighttime terrors to Yahoo.

As people's uneasiness about the current political situation is showing up on their brain's bedtime reel, researchers aren't that surprised. "We all have a mental map of our understanding of ourselves, our leaders, and our world. Any kind of event that is a threat to these maps will very likely be associated with nightmares," says Anne Germain, an associate professor of psychiatry at the University of Pittsburgh who studies sleep disorders. "So it's not just things that have already happened to us, it's any kind of event that would require some level of adaptation."


Having fucked up dreams, in other words, is a common part of the human experience. Dreams of being pursued or chased are one of the most common types of dreams, along with accidents, physical aggression, evil presences, and falling. Research has found that anywhere from 8 to 30 percent of people report monthly nightmares and 2 to 6 percent say they happen on a weekly basis. Why the range? Well, scientists aren't yet on the same page as to what the definition of a nightmare should be, so what "counts" as a nightmare can vary from study to study.

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, for instance, describes nightmares as extremely dysphoric and well-remembered dreams that usually involve efforts to avoid threats to survival, security, or physical integrity, and wake the person up. Given the stipulation that a person must be roused from their sleep during a nightmare, some researchers will use the term "bad dream" for one that doesn't result in a wakening.

But many experts will argue that point. "I think there's some flexibility in that, and I'm inclined to take my patient's word if something felt like a nightmare, whether they woke up or not," says Patrick McNamara, associate professor of neurology at the Boston University School of Medicine and author of Nightmares: The Science and Solution of Those Frightening Visions During Sleep. "If the content was still disturbing to them and they're haunted by it but didn't wake up, I'm not going to discount it." (Note: In this article, bad dream and nightmare will be used interchangeably).


What actually causes nightmares is perhaps a less contested topic in the field, and stress is definitely part of the equation. Researchers have found that bad dreams tend to spike in response to large-scale events—like after natural disasters, for example. A study published by the American Psychological Association in 1992 found a link between nightmares and the 1989 San Francisco earthquake. Over a three-week period, 40 percent of students surveyed in the Bay Area reported having one or more bad dreams about an earthquake, versus just 5 percent of a control group in Arizona.

Perhaps unsurprisingly, having a mental health disorder can also contribute to disturbing sleep sessions. A 2015 study by the American Academy of Sleep Medicine of nearly 14,000 adults found that insomnia and depression are the strongest risk factors for frequent nightmares. Substance abuse and traumatic experiences up the frequency, too. Research from Kent State University found that out of 314 participants who were recent survivors of serious car and motorcycle accidents, 25 percent were still having nightmares two weeks after the incidents and 19 percent still struggled with them three months later. For individuals with PTSD from sexual assault, nightmares can occur as frequently as six nights a week.

Even positive events like weddings and the arrival of a child can bring on bad dreams because there can still be some element of worry and necessity to change, Germain says, but nightmares can seemingly come out of nowhere, too. "The brain is not like a TV; it doesn't just turn off when you go to sleep. There are completely different types of activity in different areas of the brain when we are awake versus when we sleep," Germain says. "During dream sleep, the emotional brain remains 'online' but the frontal cortex, the area that helps us to make sense of images and control them, is less active. So when we have this intense emotional brain activity, the brain doesn't know how to make sense of it, and random negative mental images can come up."


Some experts think that random nightmares might not be so random. Tore Nielsen, a professor of psychology and director of the Dream and Nightmare Laboratory at the University of Montreal, is working on a new theory that attempts to explain where their origins. "The premise is that these types of dreams originate in early experiences of childhood adversity—things like separation from parents, inadequate care, excessive discipline, accidents, illness, bullying, or discrimination," he explains. "These early feelings and memories that should be forgotten by a hard-wired mechanism called infantile amnesia become more accessible to the consciousness and may reemerge in dreams, producing the intense feelings that may be so alien to us at the time."

But as with the definition of a nightmare, there's a whole other debate on whether or not very bad dreams have a function and what it might be. In 2000, Finnish neuroscientist Antti Revonsuo proposed his Threat Stimulation Theory which is "a media favorite," as Nielsen puts it. It basically asserts that nightmares are a way for us to practice responding to threats, and therefore offer a kind of evolutionary advantage, because once we encounter the risk in real life, we'll be better equipped to tackle it. So when the time comes for Sutton to actually flee Northampton, the theory goes, she'll be ready to do so since she had a chance to run through the scenario many times—albeit in an unconscious state.


Nielsen, however, isn't so sure that reasoning holds up. "My take is that although we do tend to dream about threats, we don't often dream about successful responses to threats, so it's a little bit of a paradox," he says. He thinks that nightmares could instead serve as a way to diminish fears by combining scary elements with neutral or positive elements and the safe context of knowing that what's happening is just a dream. "In this way, dreaming serves to assuage the associated fear," he says.

Germain recalls an instance where a person with a phobia of heights reframed a nightmare as a self-challenge. "This person dreamt that they were climbing a mountain—really distressing for someone with that fear. They were later offered the opportunity to go sky-diving, which they did not decline. It's the thinking that, 'If I can be scared to death and turn out just fine in my dream, I will probably be ok in real life.'" Germain admits it could be seen as an extreme example, but "having the opportunity to safely experience things we might fear or otherwise avoid may change our perception or willingness to try different things when we are awake."

For most people, nightmares—even ones that occur several times a week and hit on their deepest fears—aren't a problem if the bad dreams are brushed off upon hopping out of bed. But for others, nightmares may haunt them during the day and cause so much distress that they start expecting to have them or hoping not to have them, which ironically makes it more likely that they will, Germain says. "If the nightmares are frequent, but also intensify to the point where it's hard to function during the day, or people are losing sleep, then we suggest getting help."

Treatments can include a type of cognitive behavioral therapy called image rehearsal therapy (IRT) in which people literally rewrite their nightmares to have more positive endings or storylines and then rehearse the new scenario during the day. Sounds simplistic and slightly New Age-y, but it's been shown to help. Research published in JAMA found that when sexual assault survivors tried IRT, they had fewer nightmares per week and better sleep quality. One small study found that in addition to improved sleep, people who used IRT also had less anxiety and hostility.

The budding field of virtual reality could also offer solutions. McNamara is working on developing a VR therapy for nightmares that is part fear extinction and part lucid dreaming. "One of the things that causes distress in nightmares is that people feel like they don't have control over the imagery they experience. With our VR program, they can resize or paint over the imagery, or transition to other images. Once the patient learns to control their levels of stress and negative emotion when they come across those images, they could perhaps change them in their nightmares, too," he explains.

When I asked Sutton if she would consider treatment if the nightmares continued to linger, she firmly refused. "I will not let that man influence my reality to the point where I have to ingest chemicals. I don't want medicine," she says. "I don't want him to dull my brain."

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