Ancient Greeks and Romans believed dreams predicted the future. Sigmund Freud thought they expressed repressed conflicts or desires and could help people unravel the reasons for mental illness.

I take a dim view of both theories, but a new study now shows bad dreams do help us out in a completely different way.

Scientists today speculate they serve an important biological purpose: Dreams in general – good and bad – might help the brain dump excess data, consolidate important information, and keep us alert to danger. What’s more, scientists believe the kind of dream we experience could serve an important purpose, even bad dreams. Let’s take a look at the scientific evidence and what it means to your health.

Dreams Are a Training Ground for the Future

An interesting idea recently emerged from neuroscience that the experience of fear in dreams is linked to how we’ll later respond to a real threat when we’re wide awake.

Lampros Perogamvros, a sleep researcher at the University of Geneva, explored this idea, hoping to discover whether bad dreams serve any useful function.

Dr. Perogamvros and his research associates designed two studies:

In the first, researchers placed 256 high density electroencephalograph (EEG) electrodes on the heads of 18 volunteers before they went to sleep. This new, sophisticated type of EEG acquires much more data than the standard EEG of 18 to 24 sensors, providing a detailed three-dimensional electrical image of the brain.

They woke each participant up a number of times during the night and asked whether they experienced fear in their dreams. From their responses the scientists identified two brain regions implicated in fear, the insula and the cingulate cortex.

Same Fear Centers Activated When Asleep and Awake

The insula is a deeply buried area of the brain that researchers began studying in the last 25 years. It seems to be activated in a wide range of thoughts and behaviors during wakefulness, including the emotion of fear.

The cingulate cortex plays an important role in emotion, including the preparation of both motor and behavioral responses to a threat.

Dr. Perogamvros commented on their findings, “For the first time, we’ve identified the neural correlates of fear [i.e. what happens physically in the brain] when we dream and have observed that similar regions are activated when experiencing fear in both sleep and wakeful states.”

In the second study, researchers asked 89 participants to write down any dreams they could recall when they woke up, and identify all emotions they felt including the emotion of fear.

At the end of one week, researchers gave each participant an MRI brain scan. The scientists looked in particular at areas involved with emotions, not just the insula and cingulate cortex but also the amygdala and medial prefrontal cortex.

Bad Dreams Help You Better React to Stressful Situations

What happened next is described by another member of the team, Dr. Virginie Sterpenich.

“We showed each participant emotionally-negative images, such as assaults or distressful situations, as well as neutral images, to see which areas of the brain were more active for fear, and whether the activated area changed depending on the emotions experienced in the dreams over the previous week.

“We found,” Dr. Sterpenich continued, “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.

“In addition, the activity in the medial prefrontal cortex, which is known to inhibit the amygdala in the event of fear, increased in proportion to the number of frightening dreams!”

What this research demonstrates is a strong link between the emotions we feel in both our sleep and waking states. This reinforces the theory that the brain generates our frightening dreams to train itself to better react to fearful situations in our daily lives.

Or as Dr. Perogamvros puts it, “Dreams may be considered as a real training for our future reactions and may potentially prepare us to face real life dangers.”

However, according to the researchers this only applies to moderate amounts of fear. If fear becomes excessive it loses its beneficial role.

So, we should look forward to bad dreams – but not nightmares.


  1. https://www.ncbi.nlm.nih.gov/pubmed/31663236
  2. https://www.unige.ch/communication/communiques/en/2019/quand-les-reves-nous-preparent-a-affronter-nos-peurs/

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