The youngster suffers from a rare disease called progeria which turns children old before they have reached their teens.
But now having celebrated her 14th birthday she has defied all odds and to celebrate she has published her autobiography.
Like any other teenager the book, called Old Before my Time, details pop-star crushes and a dislike of school.
But it is also a moving insight into how a child copes with a disease which has resulted in Hayley having the body of a 105-year-old.
The book has been co-written with the help of her mother Kerry who contributed to some of the chapters.
She writes: ‘She definitely seemed much wiser and more inquisitive than other 20-month-old toddlers.’
Progeria takes its name from the Greek word ‘proeros’ meaning prematurely old and involves a mutant protein called progerin that accelerates physical ageing.
It ages the body at eight times the normal rate leaving Hayley with skin that is thin and papery and bones that are fragile.
Progeria patients normally die from heart attacks or strokes at an average age of 13.
‘Mum says I am one in eight million because my condition is so rare,’ Hayley says in her book.
Hayley, of Bexhill, East Sussex, turned 14 in December and is among 89 children in 32 countries living with progeria.
Mum Kerry knew something was wrong when her baby wasn’t growing or putting on weight as quickly as other infants normally would.
Her family was left devastated when she was diagnosed with Hutchinson-Gilford progeria syndrome.