Watch Claire Manning's report.
A mum from Devon has written a book in the hope of raising awareness of Sudden Unexpected Death in Epilepsy (SUDEP).
Four years ago Sophie Pierce lost her 20-year-old son, Felix Murdin, to SUDEP.
SUDEP is the sudden, unexpected death of someone with epilepsy, who was otherwise healthy.
Every year, more than one in 1,000 people with epilepsy die from SUDEP, making it the leading cause of death in people with uncontrolled seizures.
After Felix died, Sophie learnt her son had been in an 'at risk' group of the condition.
Felix had epilepsy from a young age and suffered with night seizures - one of the symptoms which put him at a greater risk.
Sophie had been on her way to visit Felix at university when she learnt he had died.
She said: "When I got there there was an ambulance outside and I just knew, I just knew. You just can't conceive of that happening.
"He was my lovely, beautiful son and every mother would say that about their son, but he was and he was really just coming into his own in life really and he was starting to live his life and that's why it was so desperately sad when he died so suddenly."
Sophie has since written a book about life after Felix's death called 'The Green Hill'.
An excerpt from the book reads: "We have a few videos, you aged about three playing the piano, screaming laughing and turning the pages of the music every so often.
"I desperately want to remember you, all aspects of you, all ages of you - perhaps I can't because my mind is dominated by the horror of your death, this is all I keep thinking about."
Sophie is now hoping to get her book published by using the Crowdfunding publisher 'Unbound', where potential readers pledge to buy a book before it's published.
She said: "I hope that the book will raise awareness about SUDEP as well, it does disproportionately effect young men like Felix, I hope that through a personal story that the whole thing of SUDEP will become better known."