A MUM has a rare disorder which means her body goes to sleep every time she laughs - or orgasms.
Jessica Southall, 20, has narcolepsy with cataplexy which sees her muscles totally relax as if she is asleep when she experiences some strong emotions.
As well as forcing her to sleep for 13 hours a day, it means the mum's body "goes to sleep" when she hears a joke, gets really upset or even when she is having sex.
Bubbly Jessica even suffered "sleep attacks" when she was in labour and has to make sure she's sitting down if she's watching something funny on TV.
At its worst the condition would see her knees buckle and her chin fall to her chest even when she giggled.
But it has less amusing side affects, like super-vivid frightening dreams and pre-sleep hallucinations which make her see shadowy figures in her bedroom.
The pregnant mum from Nottingham, north of London, said: "One minute I'll be there in stitches laughing my head off, not able to stop and the next moment my head is on my chest or I'm lying on the floor.
"I'm fully awake, I can hear everything, but I can't talk and I can't move.
"I can't respond or snap out of it until the emotion stops and to every other person it looks like I have fallen asleep.
"It happens when I orgasm too. When me and my partner were first dating it was near enough every time.
"It might sound funny - and I do have to try and be lighthearted about it - but it's horrible really.
"I just had to explain to him that it's only going to happen when he makes me feel at my very best, but it's not ideal."
Jessica started to experience extreme exhaustion aged 15, and found herself falling asleep in lessons, on the bus and even mid-conversation.
Her family, teachers and even doctors put it down to stress and a change in routine after the summer holidays - but Jessica was worried.
"I was falling asleep on the bus on the way to school, in my lessons, on the way home, as soon as I'd had my dinner - and sometimes in the middle of my dinner," she said.
"At the weekend I wasn't waking up until 3pm and then I'd go downstairs and fall asleep on the sofa.
"I think people thought I was being lazy, but I knew it wasn't right."
Still undiagnosed, she suffered her first cataplexy attack - where her muscles relax and go weak - aged 16.
She was carrying two cups of tea when her aunt told a cheeky joke - causing Jessica to laugh and then involuntarily drop the drinks after her hands went to sleep.
Soon her chin was dropping to her chest every time she giggled or heard a joke, and a fit of laughter would see her collapse to the floor, no matter where she was.
"It was pretty embarrassing when I was at school. I would just be lying their on the floor."
Months of tests and scans revealed she had narcolepsy - a rare neurological condition that affects the brain's ability to regulate the normal sleep-wake cycle.
She was also diagnosed with cataplexy - sudden muscular weakness triggered by strong emotions such as laughter, anger and surprise.
Combined, it means she falls asleep when she laughs, cries really hard, or experiences extreme pleasure - and also leaves her needing lots of sleep.
"At my worst I was full on collapsing every time I laughed," she said.
"If I was sitting down my head would just loll down on to my chest.
"It's hard to explain but I am fully awake and I can hear everything, but I can't talk or move.
"It's like I'm trapped and my body is asleep, but my brain is awake.
"It happens until the emotion stops and until then it looks like I'm asleep.
"I remember I was in McDonald's and my sister made me laugh and my head went straight on the table.
"My mum was saying, 'What is she doing?' and she had to carry me out."
She was prescribed medication usually given to children with ADHD which has the opposite effect on her - making her more alert, and less susceptible to the condition.
But bizarrely - without any explanation - her conditions only subsided when she got pregnant with daughter Briella, now one.
She suspects the "sleep when your baby sleeps" routine has helped her get more of a grip on her condition.
She still sleeps 11 hours a day and has attacks when she laughs, orgasms or sobs - but can have a little giggle without passing out.
But she did pass out twice while in labour - waking up to finder herself in "full on" contractions.
This article originally appeared on The Sun and has been republished with permission.