One day, a terrifying hereditary illness will stop siblings Hayley and Lachlan Webb from ever going to sleep again and eventually it will kill them.

The brother and sister from Queensland have inherited the extremely rare disease known as Fatal Familial Insomnia (FFI) from their family and have no idea when it will strike, 60 Minutes reports.

The rare genetic disease, which affects less than one in 10 million people worldwide, is a debilitating brain disease with no treatment and no cure.

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Queensland siblings Hayley and Lachlan Webb have inherited an extremely rare disease known as Fatal Familial Insomnia, which will one day stop them from ever going to sleep again and eventually will kill them

Anyone who has FFI is tragically destined to die because it stops them from ever falling into a deep sleep and leads to rapid mental and physical deterioration.

Hayley, 30, and Lachlan, 28, first became aware of the genetic time bomb in their family when they were teenagers and their grandmother became ill.

'In my early teens I remember becoming aware of it, aware we had this family curse,' Ms Webb said.

'My grandma started getting sick and dying. Her eyesight went, she had signs of dementia, she was hallucinating and couldn't talk. Eventually she was diagnosed with FFI, that was the first time the family even knew that FFI existed.'

Ms Webb, who is a Channel Nine news reporter, said her mother started showing the first symptoms in 2011.

Hayley, who is a Nine News reporter, is taking part in a pioneering study at the University of California to help find a cure for the brain disease that affects less than one in 10 people worldwide

Hayley and Lachlan (pictured with their parents) first became aware of the genetic time bomb in their family when they were teenagers and their grandmother became ill

The 30-year-old television reporter said she first became aware of the 'family curse' when she was a teenager and her grandmother started to show symptoms. Her grandmother passed away aged 69

'I remember leaving for work to my new post on the Sunshine Coast and mum saying 'have a great day, I'm so proud of you' and then later that week coming back and she was calling me Jillian and she thought I was the housekeeper. It was incredibly aggressive,' she said.

The aggressive disease took hold giving her full blown hallucinations and she tragically passed away after six months.

FFI causes abnormal clumps of protein that damages nerve cells and eventually causing sponge-like holes in the thalamus - the part of the brain that regulates sleep.

'Your body is not allowing you to rejuvenate at all so it's like being awake for the last six months of your life,' Mr Webb said.

Hayley's mother started showing the first symptoms in 2011 but the aggressive disease took hold and six months later she died

Hayley, pictured with her mum after she was diagnosed, said her mother had full blown hallucinations towards the end. The disease begins with exhaustion and leads to a decline in mental and physical capabilities

Hayley and Lachlan say they have no idea when Fatal Familial Insomnia will strike. There is currently no treatment and no cure for the debilitating brain disease

While there is currently no cure, the siblings are taking part in a pioneering study at the University of California being led by US couple Eric Minikel and Sonia Vallabah to help find a remedy.

The siblings have no idea when the disease could strike for them.

'My aunty passed away at 42, my mum passed away at 61, my grandmother passed away at 69 - mum's brother died at 20... we're just hoping we're not one of the young ones,' Ms Webb said.

'It could happen tomorrow but until we're in that danger zone we probably have a good 10 years up our sleeve and I am praying that there is a cure between now and then.

'I don't want to sit here while the sands through the hour glass pass waiting for it to trigger and for me to cark it. I want information, I want answers and I want a bloody cure.'

Lachlan underwent tests alongside his sister in San Francisco to help with research into the fatal disease

The siblings say they are determined not to let Fatal Familial Insomnia rule their lives