In 2000 Finnish researcher Antti Revonsuo proposed a new theory for interpreting dreams. It has become known as the “Threat Simulation Theory.”

The theory proposes that dreaming is a defense mechanism. It serves a biological function by simulating threatening events. The theory suggests that the brain selects waking events that pose a threat to your safety.

Then during the majority of dreams your brain simulates these events over and over again. The threats are replayed in various combinations.

In this way the brain is able to practice how it perceives threats. It also “rehearses” threat avoidance.

A 2006 study tested this theory using a sample of 212 recurrent dreams. It provided some support for the theory. Sixty-six percent of the dream reports contained one or more threats.

These threats tended to put the dreamer in danger. Dreamers tended to take reasonable defensive or evasive actions.

But less than 15 percent of the dreams depicted realistic situations that would be critical for survival when awake. Also, dreamers rarely succeeded in fleeing the threat.

The theory also suggests that your “threat simulation system” would be highly active if you live in a dangerous environment. It would be less active if you live in relative safety.

A 2005 study supported this proposal. It analyzed the dream reports of Kurdish and Finnish children. Results show that severely traumatized children had more dreams. These dreams included a higher number of threatening events.

But a 2008 study contradicted these findings. It tested the theory using 208 people who live in a high-crime area of South Africa. Their dreams were compared with those of people who live in a low-crime area in Wales.

The people in South Africa had more exposure to a recent life-threatening event. But they reported fewer threat dreams. Overall, less than 20 percent of dreams featured realistic survival threats. Less than two percent of dreams included an escape from a threat.

A new review analyzed the results of these and other studies. It concludes that there is strong support for the theory.

Learn more about dreams and nightmares.

By Thomas M. Heffron