How people who are blind dream

If our dreams are a reflection of reality, how does someone who experiences a different reality dream?

A new study published in the journal Sleep Medicine focused on how the blind dream. For sighted people, dreaming is primarily a visual activity: you remember images. But if you don't have the sense of sight, other sensory information--the information you rely on the most-- takes the lead.

The researchers looked at groups of people who were blind from birth (or congenitally blind), those who became blind later in life, and those who can see. Immediately after a dream, they were asked about their sensory experiences -- (What did you see? Did you taste anything?) -- as well as how they felt emotionally in the dream. They were also asked if there were any themes, like falling, or being able to fly.

Amongst the blind participants, most of the content in their dreams was made up of things they heard. 86 percent of participants experienced sounds and voices, as opposed to 64 percent of the sighted group.

The scientists basically said that the longer the person was able to see during their life, the more visual content there was in the dreams. The blind also experienced more sensations of touch in their dreams -- 70 percent versus 45 percent of the seeing group. The blind were also much more likely to taste and smell than the seeing group.

In terms of emotional and thematic content, all the groups reported similar results, but the congenitally blind group did stand out for having frequent nightmares. They were 4 times more likely to report nightmares than the late onset blindness and seeing groups.

Why might those who are congenitally blind have more nightmares than everyone else? The scientists aren't sure, but they have a theory. Nightmares are one way that our brains process and cope with threats to our safety, so it shouldn't come as a surprise that the blind tended to have nightmares about things like getting hit by a car, getting lost or losing a guide dog. It's unclear if this means that the blind experience more fear overall in their lives, generally speaking.

What do you dream about? Tell us in the comments below.