Many of us have woken up in a sweat in the middle of the night as a result of a nightmare. And those are the dreams that tend to stick with us. Now, new research suggests that nightmares are more likely to impact us emotionally through feelings of sadness, confusion and guilt, rather than fear.
This is according to a study recently published in the journal Sleep.
Dreams are defined as a series of involuntary images, thoughts and sensations that take place in a person's mind during sleep.
According to the study researchers from the University of Montreal in Canada, including Geneviève Robert and Antonio Zadra, exactly why we dream is still unknown.
But the investigators say that in the scientific community, belief holds that everyone dreams, and that these dreams usually take place during rapid eye movement (REM) sleep that most people experience three to five times a night.
The problem with nightmares
According to the researchers, around 5-6% of the population report having nightmares. And for some people, these nightmares can lead to problems.
"Nightmares are not a disease in themselves but can be a problem for the individual who anticipates them or who is greatly distressed by their nightmares," explains Zadra.
"People who have frequent nightmares may fear falling asleep and being plunged into their worst dreams. Some nightmares are repeated every night. People who are awakened by their nightmares cannot get back to sleep, which creates artificial insomnia."
Nightmares can be triggered by traumatic events in everyday life. For example, the researchers say that returning soldiers often report seeing the scenes that caused their injuries in their dreams.
They note that alcohol or psychotropic drug consumption or withdrawal may also trigger frequent or intense nightmares.
Bad dreams vs. nightmares
For their study, the researchers wanted to determine the differences between bad dreams and nightmares, as the majority of people classify these as being the same type of intensity.
To do this, they asked 572 volunteers to keep a written record of all the dreams they remembered for between 2 and 5 consecutive weeks.
Researchers say that although death, health concerns and threats are common themes in nightmares, a threatening feeling or atmosphere can also characterize nightmares.
During this period, 9,796 dreams were reported. The researchers then analyzed the narratives of 431 bad dreams and 253 nightmares from 331 adults.
The participants were asked to write down their dreams as soon as they awoke. Some of the narratives were detailed. For example:
"I'm in a closet. A strip of white cloth is forcing me to crouch. Instead of clothes hanging, there are large and grotesquely shaped stuffed animals like cats and dogs with grimacing teeth and bulging eyes. They're hanging and wiggling towards me. I feel trapped and frightened."
The investigators found that in the majority of bad dreams, the feeling of fear was almost completely absent, with more people reporting feelings of guilt, sadness, confusion and disgust. Fear was also absent in a third of nightmares.
Explaining other differences the team found between bad dreams and nightmares, Robert says:
"Physical aggression is the most frequently reported theme in nightmares. Moreover, nightmares become so intense they will wake you up. Bad dreams, on the other hand, are especially haunted by interpersonal conflicts."
She says they also found that death, health concerns and threats commonly occur in nightmares. However, she notes that sometimes the feeling of a threat or a menacing atmosphere can also characterize a nightmare.
The researchers conclude that although their findings suggest that nightmares and bad dreams have similar phenomenological mechanisms, they also show that "nightmares represent a rarer and more severe expression of the same basic phenomenon."
Last year, Medical News Today reported on a study suggesting that functional magnetic resonance imaging (fMRI) may be able to reveal the visual images the brain creates during dreaming.