Beautician Kate Sell, 43, went to bed with her husband as usual but woke screaming in a heap at the bottom of their staircase.
She realised immediately she could not move and felt searing pains in her arm, shoulder and chest.
X-rays revealed she had fractured her skull and eight vertebrae and broken her spinal cord as well as several ribs, her neck, collarbone and wrist.
Kate, who has just become a grandmother, is now paralysed from the chest down and faces an agonising wait to discover if that will be permanent.
Six weeks after the accident she has not regained any movement below the chest, although she can now feel people prodding her feet and stomach.
Kate, from Chipping Sodbury, South Glos, said: “We went to bed just after midnight and the next thing I knew it was 1.30am and I was screaming from the bottom of my stairs.
“I didn’t know where I was because I was facing two walls and it was pitch black, all I knew was that I couldn’t move.
“No matter how hard I tried I couldn’t move and I had this searing pain in my wrist and across my whole body.
“I was absolutely terrified. I didn’t know where I was or what I had done.
“I was yelling for my husband, he hadn’t heard me fall because he’s a deep sleeper.
“He came running down. I explained I couldn’t move. I tried to move my arm which made me scream.
“He took one look at me and saw there was blood coming out of my mouth and called the ambulance straight away.”
Mum-of-one Kate had sleep walked before, but only when she was in unfamiliar places and had never gone further than the bedroom door.
She went to bed as normal with her husband, Kevin, 47, on June 21 at around 12.15am and woke at the bottom of the stairs at 1.30am.
Kevin, a civil servant, called an ambulance which arrived 40 minutes later, but because of the nature of her injuries she did not leave home until 3.30am.
She added: “I obviously attempted to walk down the stairs and that was it, I was gone, but I don’t remember anything.
“I just remember going to bed and waking up facing the corner of two walls.”
Kate was taken to Southmead Hospital in Bristol where she was kept in intensive care for six days.
She was then transferred to a high-dependency spinal and neurological ward at the same hospital where she remained for five weeks.
Kate is now at the Duke of Cornwall spinal injuries unit at Salisbury Hospital where experts hope to begin her rehabilitation.
She said: “The more time I am in hospital, the more they discover my injuries.
“They initially thought I had three vertebrae broken, but I had ten levels of fracture in my back alone.
“I think there were seven vertebrae fractured. I became paralysed because everything around one of my other vertebrae was broken at chest height.
“When that broke away it damaged my spinal cord.
“I also had fractured ribs, a fractured collar bone, a fractured skull, I bit my tongue – you could see the teeth marks in the top and bottom of my tongue.
“I also had an acute fracture to my wrist. A week later I also had a collapsed lung. I didn’t do it by half – I really went for it.”
Kate’s friends are now trying to raise funds to help her live as normal a life as possible when she returns home.
Friend and neighbour, Wendy Walker, 52, has set up the Kate Sell Spinal Injuries (KSSI) fundraising campaign.
She said: “Kate would do the same for us.
“We want to raise some money to help not only cope financially as they are living on one salary but also buy any equipment she will need when she does come home.
“I also want to raise awareness of the dangers of your own home – stairs are one of the most dangerous things we all have.
“She is such a kind and sweet girl but Kate is frightened. If we can help take away some of the worry that would be brilliant.”
Kate said she was completely overwhelmed by the generosity of her friends as well as people she had never even met before.
She added: “I cried when my friend told me about KSSI. I’m completely overwhelmed but everybody’s generosity.
“Everyone is coming forth and offering to help. It’s a very strong response. It’s just amazing. I’m completely overwhelmed.
“I’m so emotional, I really didn’t realise just how many friends I had. I just thought I was a pretty sociable girl and that was it.”
To donate to the KSSI fund visit: www.facebook.com/kssikate or email email@example.com