A good night's sleep is essential, given the excessive stress people suffer from either at work or in family. Lack of proper sleep leaves people cranky and low on energy because their overworked brains are deprived of the time it needs to rejuvenate.

Deprived of sleep for days or months together could eventually lead to death, which is what happened to Lachlan and Hayley Webb's grandmother and her three children.

Hayley, 30, a Channel Nine News reporter, and her brother, 28, lost their grandmother when they were in their teens. She succumbed to Fatal Familial Insomnia (FFI), a rare hereditary disease that does not let the sufferer get deep sleep, leading to accelerated mental and physical deterioration.

The siblings from Queensland, Australia, lost their mother to the incurable disease, who died at the age of 61. The disease killed their maternal aunt at the age of 42 and their maternal uncle at the young age of 20.

Bearing the sleeping curse in their blood, the anxious siblings have been participating in a pioneering study at the University of California to find a cure for the disease, The Independent reported, citing Nine News. Eric Minikel and Sonia Vallabah are leading the study.

Hayley reportedly said during an interview on Channel Nine's "60 Minutes" show that their family became aware of the rare disease when their grandmother was first diagnosed with FFI.

"In my early teens I remember becoming aware of it, aware we had this family curse. 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," Hayley was quoted by the Independent as saying.

She recalled how the disease affected her mother's memory. "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.

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

What is FFI?

The extremely rare disease of the brain is reportedly caused by a mutation to the protein PrPC. Mostly transferred genetically from affected parents to offspring's, the disease can also develop in people with a non-inherited mutation variant called sporadic fatal insomnia (sFI).

The first case of FFI was recorded in 1765, after an Italian man died in Venice of the condition. So far, the mutated protein that causes the rare insomnia has been detected in only 40 families across the world and only 100 people have been affected. If either of the parent has the mutated gene, there is a 50% chance of the offspring inheriting the gene and developing the disease. After onset of symptoms of FFI, a patient survives for an average of 18 months.