(CNN)It took just 72 hours for me to lose my sight entirely. Just before my blindness hit, I had been laid up with an unknown virus that had left me suffering severe headaches and sweats. My body's immune system had gone haywire, responding to the virus by attacking my own nerves, causing loss of sight and mobility -- I had been struck down by biological friendly fire.
My sudden synesthesia: how I went blind and started hearing colors
Going blind was devastating. I hadn't just lost my primary sense -- I had lost my livelihood too. As a television producer, my vision was my job.
My sight started to return weeks later. I opened my eyes to a strange, supernatural view. Everything was just a swirling gray fog. I was momentarily elated that the world was no longer a suffocating black cloak -- but I realized quickly that I didn't recognize anything around me. Over time, black lines started to appear, crudely constructing windows and door frames, but little else.
Slowly the gray mist dissolved into a brown muddy haze that obscured anything more than a few feet away. Color eluded me, and people were hollow ghosts with no solidity or humanness. I often had no idea where I was, and I wondered if I would ever feel normal again.
As I recovered at home, color started slowly creeping back into my life. This was a very perplexing time, for often I felt I was seeing a color but was unable to identify it. I would stare endlessly at trees and lamp-posts, desperate to match the color I believed was there with my strange sensory experience. Bright primary colors were the first I could identify with any conviction; I struggled enormously with greens, grays and any pale or muted colors. This was not the vibrant rainbow world I was used to.
Even though my visual world was still predominantly black and white, it felt like colors were talking to me, as if my senses were communicating in ways I didn't understand. Explaining my new relationship with color only provoked confused silences, and when I described it to neurologists, I was told that nobody knew what was causing it, but that perhaps my sensory system had become cross-wired.
Color information was still being transmitted to my brain, but I was receiving only part of the message. My lifelong emotional associations with colors were still intact, even if my sight was not. I tried to use language to help myself recover. "You are green," I would tell the grass, using reminders to try and bring my normal vision back online. The more I did this, the more it worked.
I began documenting my recovery using an audio recorder. I also experimented further with using language, when looking at objects whose color I didn't know. First I would guess what color an object might be. Then, if I was wrong, my husband, Ed, would tell me the correct color. If I looked back and repeated that color out loud myself, I would often temporarily see it, albeit muted.
It was in this way that my home and neighborhood became my personal vision laboratory. My experiences were so outlandish that there were times when I couldn't believe my eyes. Yet my eyes were undamaged -- all of these strange occurrences were happening inside my brain.
My doctors told me I had experienced a rare form of monophasic neuromyelitis optica spectrum disorder, a condition that's estimated to affect just one in 100,000 people in Europe. One of my primary symptoms had been inflammation of the optic nerves, which caused my blindness. It also eventually led to my unusual form of what I now know as synesthesia -- and to my desire to find out more about it.
Synesthesia is a biological condition that causes some people's senses to cross over, so one kind of sensory response is produced by stimulation of another sense. This sensory intermixing can occur in many different ways, involving various senses, but most synesthetes are born with it. It's an entirely neurological condition, estimated to affect as much as 4 per cent of the population, at least in the UK.
One woman I met, Janet, whose name has been changed, is what is known as a grapheme--color synesthete -- colors appear in her mind's eye that correlate to individual letters or numbers (graphemes). Janet sees each letter of the alphabet as a particular color, and each letter has a different personality -- some sad, others jolly.
A university administrator, Janet had been unaware that anything was unusual until her early 40s. One wintry afternoon in the office, she was discussing the arrival of a colleague's baby and mentioned that choosing a name for a baby was so hard, particularly if your spouse chose a name that had a color you didn't like. The room went silent until one of her friends asked her what she meant.
Janet baffled her colleagues further when she told them that the first letter of a word could even put a tint over the rest of the word. Something so obvious and woven into her life was an anomaly to everyone else.
Janet is a classic synesthete, having been born with it and never knowing anything different. I've discovered that my version of synesthesia is much less common, and has quite a different personality.
My illness had been a terrifying ordeal. At the worst of it I had been unable to walk at all, but, a few months on, I was able to wobble unsteadily down the road using a stick.
One afternoon, I hobbled around the streets of south-east London on the arm of my husband. Taking small, tentative steps I forced my rubbery legs to move.
As Ed and I slowly trundled along the road we came across a row of recycling bins. The moment I became aware of the nearest bin, I stumbled forward on my own. Fixating on the lid, I could see what I can only describe as a firework display. I knew I was registering the color blue, but it was spitting and fizzing like an erratic sparkler. Mesmerized, I reached out my right hand, and feeling the hard plastic spoke the word "blue" out loud. The sparkling stopped immediately, and the bin became a flat, rather lifeless blue. Cautiously I stepped back, but to my astonishment, the blue fizzing started up again.
We might have been able to put this down as a one-off hallucination (I was having lots of those as my vision returned) but it wasn't. I found I could repeat the exercise and the bin would alternate between flat blue or erratic sparkling blue depending on whether I touched it or not.
I started hunting out other objects that might fizz and sparkle -- but I quickly learned they had to be blue, and located in front of me. For a time any bright blue object would fizz and spit erratically. Through my touch, the effervescence would calm, become stable and inert, and when I stood back, start fizzing again.
I came to call this brief time during my recovery my "blue period". I was seeing something that, as far as I knew, nobody else had ever experienced. It became a deeply personal and emotional journey, and those blue sparks offered me a glimmer of hope that my visual system was repairing itself -- albeit in a strange and unique way.
There is no absolute explanation for my blue period, other than that my brain had suffered a huge trauma and was continually adapting to stimuli around me. Acquired synesthesia, as it is known, develops temporarily during a person's lifetime, often provoked by hallucinogenic drugs, brain injury or sight loss.
In my case, I had likely experienced two forms of acquired synesthesia: one connecting color and touch, and one connecting color and spoken language. It is clear, however, that mine was unusual. In classic forms of color synesthesia there is no intelligible link between a certain stimulus (such as one of Janet's letters) and the color sensation it provokes. But for me, color words were helping me see those same colors.
And while touch was stimulating a response for me, this was about stabilizing the color that was already there -- not creating one.
After I had recovered sufficiently, I was put in touch with Giles Hamilton-Fletcher at Sussex University, who specializes in synesthesia and blindness. He is also a part of the UK Synaesthesia Association, a charity that aims to improve understanding of this extraordinary condition.
Giles invited me to the 2017 Open Senses Symposium at the University of London. There, he showed me a sensory substitution device (SSD), which allows information from one sense, usually vision, to be re-routed through another sense, enabling people with visual impairments to produce some semblance of vision. Pointing at some red fabric, Giles explained that a sensor would translate its color into an intuitive sound. I experimented moving the fabric around under the sensor, resulting in a high-pitched synthesized sound from the headphones. As I inched the fabric closer up towards the sensor, the sound became more staccato, offering me not just an auditory representation of the color but awareness of where it was in space.
An SSD like this one converts a visual signal to a sound, which the brain can then learn to convert back into vision. Giles is interested in the relationship between this kind of sensory substitution and synesthesia. After all, translating one sense into another is what synesthesia is, in a nutshell. Because of this, SSDs are one of the first technologies to meaningfully demonstrate just what synesthesia -- or at least one kind of it -- might feel like to those who have never had it.
Daniel Hajas is a physics undergraduate at Sussex and has been blind since he was 16. He first heard about Giles and the SSDs when Giles was looking for blind students to test the devices. Daniel found one called the Creole could help him access vast swathes of visual, color-coded data, opening a door back to color that he had previously thought shut.
In physics, a crucially important image is the cosmic microwave background radiation map, a kind of speckled blue orb, sprinkled with patches of yellow, and red streaks. This color map signifies the location and intensity of cosmic radiation in the universe resulting from the Big Bang.
Daniel can't see it. But, using the Creole, he can hear it.
The Creole works as a stylus with a sensor at the end and a tablet connected to a laptop. On the laptop screen is the radiation map, and by placing the stylus somewhere on the tablet, Daniel can make the Creole produce sound that corresponds to the color of the equivalent part of the map.
As he moves the stylus, there are erratic beeps and a low droning sound. With occasional pauses, Daniel can accurately identify the colors -- even nuanced shades. By employing the principles of synesthesia, Daniel is hearing the colors he needs to see.
Both Daniel and I learned to exploit an unconscious relationship with color in a way that benefited us. Our stories are different, but you might say synesthesia has opened both our eyes.
Several years on, I still have profound color loss and some visual disturbances. I still think about my blue period. While at times it was eerie, there was something magical about it. Few have seen anything like what I have seen. Most synesthetes are born with the ability, but I have the unique perspective of having experienced a time before, during and after it.
My brief time as a synesthete showed me an innate association that I believe I unthinkingly tapped to boost my recovery. The extent to which my newly found synesthesia helped my recovery is likely to remain shrouded in mystery, both to me and, for now, to science. However, I can't shake the feeling that my synesthesia acted like a magician, pulling back the curtain on the visual world.
My brain knew what to do -- it was showing me the colors I needed to see, even when the world went dark.