Patient describes life with ultra-rare incurable disease that people call 'their worst nightmare'

A person has described what it is like to live with an incurable and deadly condition, which has been described as people's 'worst nightmare'.

The condition is part of a group known as 'prion' diseases, an extremely weird and unpleasant set of conditions.

Characteristics of prion diseases include that they are progressive, meaning they get worse over time, they are incurable, and they are fatal.

So a prion disease is really not a condition that you would want to have.

There are many ways you can get one, such as consuming infected flesh, coming into contact with an infected fluid, or in the case of this one in particular, having at least one parent with the genetic predisposition to it.

The condition is a form of insomnia. (Andrii Lysenko / Getty)

In fact, the condition is a type of insomnia. But we're not talking your regular garden variety insomnia here, this is far more serious.

The condition is called 'Fatal Familial Insomnia' or FFI, and unlike other kinds of insomnia there is no cure.

Not only that, but your body finds it simply impossible to sleep no matter how exhausted you become.

Once the condition begins to manifest, you effectively stay awake permanently, until eventually you die from symptoms brought on by exhaustion and sleep deprivation.

This occurs in a number of different stages, beginning with the first stage of around four months that includes insomnia that results in paranoia, panic attacks, and phobias

The second stage lasts about five months, and includes hallucinations and panic attacks.

This is followed by a stage lasting for roughly three months in which the patient starts rapidly losing weight.

Finally, the patient develops dementia before becoming completely unresponsive.

This final stage lasts for around six months before the patient's death.

The condition is terminal. (Yoss Sabalet / Getty)

It is possible to test if someone has the genetic mutation which causes the condition.

One patient took to social media to describe their feelings of having the condition.

They wrote on Reddit: "It was the worst feeling in the world knowing that I was going to die soon and it was only after my diagnosis that my already existing insomnia is growing worse.

"It's likely to be hereditary so my family is taking tests to see who has it.

"My parents except for me and my siblings don't have it, I feel so bad for my parents knowing that one day the will go childless.

"They act strong around me but i know inside they are hurting so much and they feel so bad that they have passed this on to us. Even if that's true I still love them."

There are researchers investigating possible ways to treat the condition, but for now it remains incurable.