I was on my way home when it first happened. Walking back from the train station, the same way I walked every day, twice a day, I suddenly felt as if I no longer knew where I was or who I was.

Had these houses always looked like that? Why was everything so bright? Who am I and what am I doing here? Am I here at all, and if not, where the hell am I?

These thoughts crashed through my mind at a terrifying rapidity. Familiarity had been ripped from beneath my feet and I was left swaying in a world I could recognise but not comprehend as normal.

These strange sensations began to follow me. At work, I found myself serving customers and wondering if they really existed or not. Around my friends I would zone out of conversations and watch myself as if from the rear of the room. My hands were no longer mine but belonged to a body I knew I inhabited, yet felt barely alive in. I felt estranged from reality – my body detached from my mind and the world around me, my life unfolding behind a glass veil.

After months of grappling with these bizarre feelings, and too embarrassed by them to seek help, I turned to the internet in search of reassurance that these experiences were not the first stage of madness or cognitive decline. According to Doctor Google, this pervasive state of feeling “unreal” is one of the first symptoms of Depersonalisation/Derealisation Disorder (DPD), a psychological condition in which the mind’s perception of itself and the external world become warped and distorted.

Not wanting to rely on the internet, I affirmed my knowledge with a mental health worker who assured me that DPD is a normal response to prolonged stress, anxiety, depression, recreational drug use or trauma. Depersonalisation refers to a sense of alienation from selfhood, and derealisation describes feelings of detachment from one’s surroundings.

DPD is one of the brain’s coping mechanisms against a perceived threat. When the mind decides it can no longer endure a reality deemed too bewildering to handle, it copes by shutting the world out. This is somewhat ironic – after all, the last thing one needs when one feels anxious or fearful is a heightened and acute sense of having totally lost the plot.

If you have never experienced the terror of no longer being able to fully comprehend a once familiar reality, this idea of estrangement from one’s body and surroundings may seem understandably bizarre and unbelievable.

A recent Guardian article quotes studies that have suggested up to two per cent of the population may experience DPD at some stage in their life. Despite this, it is rarely discussed. Perhaps this is also due to the fact that the brain suppresses memory during the attacks, making the feelings and sensations of “unreality” difficult to recall once the mind has regained a sense of safety.

While there is comfort in knowing that DPD is not a psychotic disorder (i.e. sufferers are never convinced of an alternative existence) in some instances this tentative yet unwavering connection to reality can make things worse. You know that these feelings of alienation are amiss, but emotionally you fail to accept this logic and descend into panic.

DPD can also be difficult to treat because the more you focus on the feelings, the more you exacerbate them. While cognitive behavioral therapy has been known to benefit some cases of DPD, the lack of awareness and limited research has stymied attempts to prove effective treatment programs.

Over time, I have learned not to fight DPD but instead accept its visitations as temporary. Meditation and yoga are some of the best antidotes; for me, they are as much a prevention as a cure. Awareness is also one of the most important assets in understanding and eventually overcoming the loneliness and fear associated with DPD.

Although the stigma surrounding mental illness has thankfully begun to break, we still come to associate people who suffer with those who live in the shadows – people who are not us. The rambling homeless person or the Woody Allen­type neurotic are stereotypes we rely on in order to mitigate our fears about the subversive nature of mental health issues.

And yet, these do not uphold reality. My family and friends had little knowledge of how I was feeling during my experiences of derealisation and depersonalisation – partly because I didn’t talk about it, but also because I was able to uphold a semblance of normality. It can be hard to talk about DPD seriously, especially amongst young people who are often invested in exploring the limitations and possibilities of altered consciousness.

DPD is not fun, and it certainly isn’t funny. For all its attempts at supplanting you in the unknown and probing your relationship with reality, the destabilising nature of this condition remains very real.