Nightmares have always been a dreaded human experience. In certain cultures, they were thought to be premonitions of the future. It was this ominous notion that prompted indigenous cultures to construct dream catchers. When a bad dream entered the dreamer’s sleep, the webbing of the dream catcher supposedly trapped this nightmare. The first light of morning then caused these bad dreams to melt away.

Despite our inherent fear of nightmares, current research has demonstrated that they may be a necessary and functional aspect of dreaming.

The Dream and Nightmare Laboratory, which is associated with the University of Montreal, and Sacred Heart Hospital, conducts research in the areas of the scientific study of dreaming and sleep disorders. While this laboratory does not interpret dreams or give sleep consultations, it aims to provide insight into the important psychological role that dreams and nightmares play.

The brain appears to apply the same neurological machinery during the night and day to examine past events. Dreams allow the brain to process conscious experiences and regulate emotions.

Over the course of the night, sleepers experience a variety of neurological and physical states, with the rapid eye movement (REM) sleep period being one of the most prominent. Dreams occur most frequently during REM period.

According to the researchers at the Dream and Nightmare Laboratory, this period of sleep is characterized by an emotional ‘surge’ that unfolds over time. Specifically, they believe that the content of one’s dream is used as a mechanism to regulate or contain this surge.

Essentially, dreaming reduces the intensity of the emotional surge, allowing these feelings to be processed through a series of dreams that unfold over successive REM periods of the night. In this manner, dreaming acts as a method of emotional problem solving.

Nightmares, like dreams, are connected to the REM sleep period. They occur when dreaming cannot contain the emotional surge, causing the dreamer to undergo disturbing and highly realistic mental experiences. Many can relate to the feelings of anxiety, fear, or terror brought on by nightmares.

Despite the inner turmoil they cause, researchers at the Dream and Nightmare Laboratory think that these bad dreams have a function. In cases of bereavement, for example, vivid images of the deceased may persist for years as hallucinations, illusions, and intense dreams. Dreams of the dead should not necessarily be feared. Nightmares like these may help individuals accept the reality of his or her loss and facilitate a sense of closure.

Nightmares are also an excellent indicator of one’s emotional state. “Whether or not a bereaved person finds dreams comforting likely is a reliable indicator of if the mourning is taking a favourable course,” according to a paper written by UdeM researchers Tore Nielson and Jessica Lara-Carrasco.

Craig Webb, a McGill graduate who has helped with dream and lucid dream research at both Stanford and UdeM, is the executive director of the nonprofit Dream Research and Experimental Approaches to Mechanisms of Sleep (DREAMS) Foundation. He has a similar view to offer.

“Whether bad dreams are full-fledged nightmares, anxiety dreams, or just a bit unsettling, they serve as ‘pressure-release therapy,’” Webb said in an interview with the site WebMD. He explained that, “nightmares are a very bitter but much-needed medicine.”

The DREAMS foundation postulates that nightmares serve an important purpose by sending the dreamer a valuable emotional message. In addition to an emotional check-up, nightmares may have also played an important role in evolution. In the past, dreams often warned people about dangerous situations. If a tiger killed in a nearby village, a nightmare would keep one anxious about that happening to one’s own village.

Research conducted by Erin Wamsley, a sleep scientist at Beth Israel Medical Center and Harvard Medical School, also supports the teaching function of dreams. Mainly, she focuses on the relationship between memory and the different stages of sleep. Both dreams in non-REM sleep and the vivid dreams of REM sleep are important in terms of teaching the dreamer based on experiences from the day.

This evolutionary role of dreams may explain why nightmares are still present in today’s society. It seems they are evidence of the role of dreams in an ancient fight or flight mechanism. With all these functions in mind, perhaps nightmares are not so undesirable after all.