Neurosurgeons from the University of Copenhagen have asked this same question. They have studied the dreams of 25 participants, 11 of which have been blind since birth, while the others lost their sight after the age of 1.
Over the course of 4 weeks, the volunteers in the scientific experiment kept a diary in which they described their dreams every night.
The end results of the study showed that blind people have much more vibrant dreams than those who can see. Those of us who rely on our sight in real life, focus primarily on visual objects in dreams.
But in the dreams of blind persons, sensations are much more varied - sound, touch, taste and smell.
"I've been blind since birth, I've never seen in my life. Therefore - my subconscious has no idea what it means to see. The routine of my daily life is what it has to work with. Everything is subjected to smells, sounds, tastes and touch, " shared one of the volunteers at the end of the experiment.
Those participants who lost their vision at a later stage in life say that they experience vivid dreams. In their diaries they describe specific objects, around which the event in the dream takes place.
Researchers report that nightmares are significantly more common in those who have been blind since birth. Examples include getting lost, being hit by a car, losing their guide dog or falling into a hole.