Bad dreams actually have a psychological benefit when you're awake

The next time you awake in the middle of the night, drenched in cold sweat, take a second to thank the bad dream that disturbed your rest. That scary dream may have actually made your brain better at managing fear in in real life.

The content of your bad dreams may not be based in reality, but your body’s responses to those dreams are very real. Bad dreams activate the same regions of the brain that are flung into overdrive during real scary experiences, according to a study published in October in Human Brain Mapping.

These regions of the brain, once ignited, not only make bad dreams feel that much more visceral — their activation can actually help people handle the fears they encounter in real life. However, it’s a slippery slope: Bad dreams can help but fully-fledge this is way too intense nightmares do not.

Accordingly, Lampros Perogamvros, a sleep researcher at the University of Geneva and the study’s lead author, says dreams can be considered to be “real-life training for our future reactions and may potentially prepare us to face real-life dangers.”

These results are based on two experiments. The first was conducted on a sample of 18 adults who slept in a lab at the University of Wisconsin Madison. During one night, the participants were repeatedly awakened by the scientists who asked them whether their dreams were frightening. Then the scientists scanned the participant’s brains.

When the scientists woke up the dreamers, they found activation in the insula, which is part of the brain’s “fear network” the midcingulate cortex, an area involved in goal-oriented actions, like escaping quickly from dangerous situations.

In a follow-up experiment at the University of Geneva, 89 new participants kept dream diaries for a week (they slept at home), and also had their brains scanned in the lab. This time, scientists found a striking pattern in the brains of people who often experienced fear in their dreams. When they were awake and viewed images of distressful situations (like assaults) they had less activation in the insula or amygdala, and more activation in the medial prefrontal cortex.

That’s significant because the amygdala and insula are automatically activated during frightening times. This study posits that it’s the medial prefrontal cortex activation that seems to be most significant because this region is involved in creating a rational response to that fear. It’s the soothing voice that reminds you a scary movie is fake, or that tarantula on the screen can’t actually hurt you.

People who experienced fear more often in dreams tended to have more activity in that area of the brain that helps put fear into a manageable context. They also showed less “autonomic” responses to scary images when the scientists measured their pupil size, suggesting that they weren’t as afraid of the images as those who didn’t have bad dreams.

Taken together, that suggested that their brains were just better at coping with the fear, partially, this team proposes, because they had gained valuable experience dealing with bad dreams at night. This research fits well with other studies that suggest dreams that both help the brain consolidate emotional memories and act as a simulation of reality that the brain can ultimately learn from.

That said, there is an important caveat to consider: This new study says that the dreams themselves can’t be too scary, otherwise, the benefits of a bad dream could be eclipsed by negative consequences.

Nightmares, which can feel emotionally overwhelming often end up disturbing sleep, can actually increase negative emotions like loneliness and anxiety. Traumatic nightmares, which sometimes follow life-altering bad experiences can be even more psychologically damaging. The authors argue that there is no value to be had these types of horrifying dreams.

“We believe that if a certain threshold of fear is exceeded in a dream, it loses its beneficial role as an emotional regulator,” Perogamvros said.

However, in the right doses, a bad dream or two may not be so harmful. It may come as small comfort for people who feel plagued by bad dreams, but ultimately they may have an advantage during the day.

Abstract:

Recent neuroscientific theories have proposed that emotions experienced in dreams contribute to the resolution of emotional distress and preparation for future affective reactions. We addressed one emerging prediction, namely that experiencing fear in dreams is associated with more adapted responses to threatening signals during wakefulness. Using a stepwise approach across two studies, we identified brain regions activated when experiencing fear in dreams and showed that frightening dreams modulated the response of these same regions to threatening stimuli during wakefulness. Specifically, in Study 1, we performed serial awakenings in 18 participants recorded throughout the night with high‐density electroencephalography (EEG) and asked them whether they experienced any fear in their dreams. Insula and midcingulate cortex activity increased for dreams containing fear. In Study 2, we tested 89 participants and found that those reporting higher incidence of fear in their dreams showed reduced emotional arousal and fMRI response to fear‐eliciting stimuli in the insula, amygdala and midcingulate cortex, while awake. Consistent with better emotion regulation processes, the same participants displayed increased medial prefrontal cortex activity. These findings support that emotions in dreams and wakefulness engage similar neural substrates, and substantiate a link between emotional processes occurring during sleep and emotional brain functions during wakefulness.