Recurring dreams often bring us back to the same situations, such as an unreviewed exam, a speech, or being attacked. But why do these unpleasant dreams recur?

Many people have recurring dreams throughout their lives. Studies show that about 75% of adults have had at least one dream. These dreams may be similar each time, or they may have a common theme, place or person, but the events are different each time. This is different from dreams caused by post-traumatic stress disorder, in which waking memories are repeated almost exactly. While researchers are still not sure why we have recurring dreams, recent studies have helped to explain patterns in the frequency and content of dreams, as well as the circumstances that often lead to them.

Studies have shown that recurring dreams are usually negative, although not always. A 2022 survey conducted by Michael Schredl, director of the Sleep Laboratory at the Central Institute for Mental Health in Germany, showed that two-thirds of adults reported that their recurring dreams had a negative undertone. These dreams usually involve situations such as being chased, being late, or failing. On the other hand, positive recurring dreams usually involve themes such as flying or discovering new things in familiar places.

The reason why negative dreams are more common is not entirely clear.Schredl explains that dreams tend to exaggerate the emotions we feel when we're awake-sometimes small emotions or situations that we can't easily change. “In dreams ,”he says , ” such emotions become more intense , even though the connection is not always as clear .

Psychology and neuroscience offer additional insights. A common psychological tendency known as negative bias refers to our natural tendency to focus on unpleasant thoughts, emotions or social interactions. This bias stems from our subconscious need to address negative situations that may threaten our existence. During sleep, our dreaming brain activates areas associated with emotions, which weakens the filter between thoughts and feelings. This may make us more prone to negative dreams.

Studying recurring dreams has been challenging because it is difficult to control them in experiments. However, common events such as the 9/11 attacks or the COVID-19 pandemic have provided researchers with a way to study dream patterns. People who experience such collective traumas often find a significant increase in recurring negatively colored dreams afterward. For example, during the pandemic, researcher Deirdre Leigh Barrett collected more than 15,000 dream reports. Her findings showed a two- to four-fold increase in dreams involving fear, illness and death compared to before the pandemic. Common dreams included watching loved ones become ill, seeing swarms of insects (which may be linked to viruses), and experiencing disasters such as tidal waves.

In the early stages of a pandemic, dreams tend to be more realistic and filled with fear and anxiety. Over time, these dreams become less frightening, but still unpleasant, with themes of social embarrassment, such as being the only person in public without a mask. Barrett explains , “It's called the ‘continuity hypothesis’ , If we don't deal with our emotions during the day , our dreams at night will deal with them instead .”

Barrett and other experts emphasize that negative repetitive dreams are common and normal. There are steps people can take to better control these dreams. One effective method is called imagery rehearsal therapy, which involves repeatedly visualizing the happy ending of a nightmare before falling asleep. Nirit Soffer-Dudek , a psychologist at Ben-Gurion University in Israel , also advises people to maintain good “ sleep hygiene ” . By keeping your sleep schedule consistent, avoiding screens before bed, and limiting your caffeine and alcohol intake, you're less likely to fall asleep while anxious. “The key,”she says, ”is to establish clear boundaries between waking life and sleep so that anxiety doesn't carry over into dreams.