Nightmares, or bad dreams, have always been a part of sleep. However, some people have had a much harder time than others dealing with the demons that only exist in their dreams. A study conducted in Denmark has been able to conclusively prove that it is the blind who are more prone to suffer from excessive nightmares than those with good vision, Inquisitr reported.

The Danish study, published in the journal Sleep Medicine, shows that an average of 25 percent of the dreams experienced by people born blind are nightmares. On the other hand, only six percent of the dreams of people with normal vision fall in the category of nightmares. What is equally interesting is that people who are born blind have a much higher chance of experiencing a nightmare than not just sighted people, but even compared to those who lost sight later in their life.

Over a period of four weeks, the team of scientists from the University of Copenhagen and Glostrup Hospital followed 11 people who were born blind, 14 who had become blind later in life, and 25 normally-sighted people. They asked participants to take note of what they dreamt. The results were quite consistent with the hypothesis initially established.

People with sight reported about 6 percent of their dreams were nightmares, while those who lost vision later in their life experienced nightmares only 7 percent. However, those who were born blind said over 25 percent of the visual content in their dreams consisted of a nightmare.

What were the nightmares? Explaining the phenomenon, study lead-author Amani Meaidi, a research assistant at the Danish Centre for Sleep Medicine at Glostrup Hospital and BrainLab at the University of Copenhagen, said, “The study confirms an already existing hypothesis that people’s nightmares are associated with emotions they experience while awake. And blind people apparently experience more threatening or dangerous situations during the day than people with normal sight.”

Essentially people without visual sensory input dream to a much greater extent in terms of sounds, tastes, smells, and touch, as they have to rely greatly on these senses in absence of vision, a sensory input system that sighted people unknowingly rely heavily on.