Jody Robson, 24, from Birmingham, saids she can fall asleep for up to 11 days at a time and she fell into a long stupor one day before her first child, Harley, was born.
Robson explained that when she properly woke up two weeks later, her husband Steven, 29, 'had to introduce her to her son' and explain the events of the birth.
"It upsets me because I don’t remember giving birth and it’s supposed to be a precious moment," she said.
"I think that’s the most upsetting episode I ever had. It gets me emotional because I missed it."
Although she has not been formally diagnosed, Robson believes she has Kleine Levin Syndrome, a rare neurological disorder which leaves people unable to awake from sleep for days.
Harley is now six and Robson and her husband also have a second son, three-year-old Riley.
The mum-of-two said it's not only the birth of her first son that she has missed, she has also slept through many moments in her children's lives.
"I have missed out on so much," she said. "The first year with your first child is really special and I missed out on a lot.
"I had seven episodes the first year Harley was born. I was asleep pretty much most of that year. It is very frustrating.”
While Robson is asleep her mother and husband help look after the children.
As she can be asleep for days, her husband must wake her at least twice to eat a snack, drink water and go to the toilet.
But while he can momentarily wake Robson to fulfill her basic needs, she falls straight back to sleep again.
Robson's typical episode consists of at least a week’s sleep and then two weeks of recovery.
"The sleeping part is not so scary – it’s the recovery afterwards," she said.
"You are scared that you are not going to be out and back to normal again and the days just drag away."
Explaining what it feels like when she falls into a deep sleep, Robson said: "One moment I’ve closed my eyes and the next I’ve woken up and it’s two or three weeks later.
"At Christmas 2014 I fell asleep on Christmas Eve and didn’t recover until January 12, 2015.
"I don’t remember anything about Christmas. It was upsetting that my children were in the living room or a relative’s house opening presents and eating Christmas dinner like a normal family and I’m on my own asleep in bed."
The mum-of-two said her first experience was when she was just 12 and living in Alicante, Spain.
Robson has not yet been diagnosed. She has been tested for epilepsy and narcolepsy – with negative results.
The KLS condition is very rare and Robson said doctors are researching the condition.
Despite the struggles she faces, Robson said she knows to treasure every day she is awake. Trips to the park, days out to the zoo and even playing at home or watching TV are moments she cherishes.