Snoozing Vision of Blind People

Deepika Biswakarma, M.Optom

Optometrist, Suvidha Opticians, Jammu & Kashmir, India

One of the strangest visions we experience while we are asleep, isolated from the outside environment and without receiving any new sensory stimuli are considered here as snoozing vision and called as dreams. Our mind creates a series of colourful pictures, images, stories while we are dreaming, and they seem real before you wake up. But, what about blind people!  Many of us heard and even it is shown in several movies that a person who is blind sees only black colour in their dreams or only hears different sounds in their dreams. Are dreams of blind people similar to that of sighted people or is it different?

To give a concrete answer to this is not easy as it is difficult for blind people to figure out what a dream means and dream interpretation is completely subjective.

Dreams are lifelike hallucinations based on your recent activities, incidents, conversations, or various other strange and familiar scenarios. During sleep our body periodically cycles through four different stages which are Stage N1, Stage N2, Stage N3 (all of three are Non-REM ) and REM stage (Repetitive Eye Movement). Most dreams occur during the REM stage of sleep when our eyes move quickly underneath our eyelids.⁽¹⁾ During REM stage prefrontal cortex is less active but brain waves are almost as active during REM cycle as they are when we are awake.

Previously conducted sleep studies have shown that congenitally blind people do not see any visual contents in their dreams just as they do not experience anything visual while they are awake. The reason behind this was believed that congenitally blind people experience fewer eye movements during REM stage.⁽²⁾ As I already mentioned that mostly dreams occur in REM sleep stage, where eye movements are hypothesised  to correlate to visual dreams. However, the fact that people who become blind at later age also experience fewer eye movement during REM stage, yet they experience visual dreams because dreams arise from visual memories that are stored in brain thus this proves the above hypothesis of monochromatic dreams for blind people stands rejected.⁽²⁾

Current evidence suggests that congenitally blind indeed experience visual dreams.⁽³⁾ However, it is difficult to find out what exactly they see. It is very challenging for them as well to describe what they see because they don’t know what visual image looks like. Scientists found in EEG report that vision related electrical activities in the brain during sleep of blind people is similar with sighted people.⁽²⁾ This means what happens during sleep is similar for both blind and sighted people. Although many blind people experience less visual image.

Congenitally blind people dream less intensely than sighted ones. The visual components of their dreams do not form from visual memories, rather visual sensation arises from electrical fluctuation originating within the brain.⁽³⁾ This means they dream more intensely in sound, smell, touch sensation, they probably see spots, colours, flashing of lights but do not see detailed visual images. And, they don’t even know how to describe that sensation.

Number of earlier studies concluded that blind at early childhood before the age of 5-7 years see varying degrees of visual content in their dreams. Whereas, who become blind after the age of 5-7 years see fully visual content in their dreams.⁽²⁾ On a related note, brain scans have found that all human dreams in visual images before they are born.⁽³⁾

References:

1. Why do we dream? https://health.clevelandclinic.org/why-do-we-dream
2. What do blind people dream about? https://www.sleepfoundation.org/dreams/can-blind-people-dream
3. Do blind people dream in visual images?  https://www.wtamu.edu/