I love getting fascinating and hard-to-answer questions on Twitter, like this one:
Great question, @ecrinn_97! I had to do a lot of research for this one. And it’s hard to find because it’s very difficult to do objective research on this subject. Dreaming is a subjective experience, so it’s very hard to categorize or substantiate dreaming.
One thing we definitely know, however: Blind people do dream. When you sleep, your brain waves change into different stages of unconsciousness. In deep sleep, stages 3 and 4, the brain waves are at its slowest. No dreaming takes place. However, when the brain switches to REM (rapid eye movement) sleep, the person can experience dreams that come from previous experiences, the unconscious or the imagination. REM brain waves, in fact, are very similar to the brain waves one generates while awake.
For those who are blind, what they see depends on whether the person was blind at birth or became blind later in life. Those blind from birth may not “see” anything according to how those with vision might define it, but they still experience sensual stimulation of some sort. If their brain has never experienced visual stimulation, there should be no reason for it to manifest in their dreams. It would instead manifest experiences that reflect the person’s stimulatory input. For example, if a person with normal vision dreams about his or her mother, he or she may envision her face, clothing, hair, or facial expressions. A blind person may instead dream about his or her mother’s tone of voice, touch or even smell.
However, if one formerly had vision but lost it in late childhood or adulthood, evidence does show that they do have some visual dreams. However, those who lost their vision before the age of five don’t have visual dreams, as if they were blind from birth. They may not have retained enough visual imagery to dream visually.
Learn more about dreams, from the most common ones to what they may indicate about your health. And while I’m at it, I’ll remind you all that it’s important to get eight hours of sleep every night, and to try to wake up and go to sleep and the same times every day. Check out our sleep hub for tips on getting more restorative sleep