At least half of adults report having occasional nightmares — this number even goes as high as 85 percent. While some of us accept it as just a part of everyday life, usually those of us who rarely have them, there are those who have their own rituals to avoid having uneasy dreams — whether it’s not eating a few hours before bedtime, or avoiding darker reading material at night — maybe skipping the evening news for that reason. They may fall asleep hoping for pleasant dreams, or that they at least won’t remember what they dreamt the night before, but it seems that even nightmares may play a practical purpose.
While the material we dream about has fascinated both researchers and lay people alike for a long time, being analyzed for whether they had deeper meanings or were meant to be warnings sent by our subconscious — of failing health or of an imminent death in the family. Now, the prevailing view is that the dreams themselves don’t have much of a subtext — they’re just scraps of things we’ve thought about during the day while we were awake. The experience of dreaming, however, could provide benefits in itself — and a new study suggests that nightmares can help us recalibrate our brains to better manage a fear response when we’re awake.
Researchers at the University of Geneva decided to look into dreams a bit further. If their content is no more significant than the usual patterns we happen to see to make sense of everyday life, then maybe dreams serve another evolutionary purpose. Doing a survey of test subjects, they found that the respondents who reported experiencing more nightmares were also able to better regulate their emotions in the face of fear.
“For the first time, we’ve identified the neural correlates of fear when we dream and have observed that similar regions are activated when experiencing fear in both sleep and wakeful states,” said neuroscientist Lampros Perogamvros from the University of Geneva who was involved with the research.
We’ve already known for some time that sleep affects our moods, but exactly how much remains a point of contention for researchers like Perogamvros. We know that our emotional intelligence benefits from a good night’s sleep, possibly because rapid eye movement helps to stabilize our negative emotions, and also helps to suppress unpleasant memories, but the question remains whether our emotions can actually echo through our dreams.
The amygdala, for example, which is typically associated with emotions like fear, is known to be active during sleep, and if less active than normal, it reduces the intensity of our dreams — making it more likely that we’ll forget them in the morning. This could be something of a correlation, but some researchers propose a “threat simulation theory,” suggesting that the brain rehearses dangerous or traumatic events through dreams — and why we might act in ways where we surprise ourselves in real life dangerous situations. Other models simply suggest that a night of uninterrupted sleep can help us to resolve emotional conflict, reducing extreme moods the next day.
Eighteen study participants underwent high-density electroencephalography (EEG) in which their brain activity was monitored while they slept. Researchers awoke them for brief intervals throughout the study, and interviewed them about their dreams — particularly whether or not they felt scared before being woken up.
An analysis of the EEG results showed activity in two particular regions of the brain: the insula and the cingulate cortex. Both of them are involved in fear conditioning, like the amygdala. The insula is activated when we experience a high stress environment, and it also regulates emotions while we’re awake. The cingulate cortex also works to prepare our bodies for potential threatening situations.
The researchers decided to expand their study — assigning 89 participants to write a dream diary for a week, documenting their dreams after they woke up, as well as how each one made them feel. After they finished the week, the subjects were placed in an MRI machine and then given emotionally negative images to look at, as well as neutral scenes — in order to evaluate if the emotions they experienced in their dreams prepared them for what they witnessed in the real world.
“We found that the longer someone had felt fear in their dreams, the less the insula, cingulate and amygdala were activated when the same person looked at the negative pictures,” said neuroscientist and co-author Virginie Sterpenich.
Sterpenich also noted that activity in the medial prefrontal cortex, known for suppressing the amygdala in frightening situations, increased along with the number of bad dreams reported by patients.
For bad dreams where frightening events are kept to a moderate level, one where you may experience floating in water or falling, for example, the brain could be recalibrated in these experiences — allowing you to think quickly in a dangerous situation later down the road.
However, in nightmares that interrupt sleep and have high levels of fear, the authors are a bit more skeptical — saying that these could have a negative effect on our emotions. They plan to study recurring night terrors further in a subsequent study, as well as the effect of positive dreams.
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- Imagine That — Imagination Is Lot Like the Real Thing (To Your Brain)
- Sweet Dreams Are Made of This: An Interview with J. Allan Hobson
- What Happens in the Brain When We Dream?