Most people love surprises, but they are agony for Caitlin Wallace, who collapses whenever something unexpected happens.
The 26-year-old suffers from cataplexy, where moments of extreme emotion cause muscular weakness. This can range from a slackening of the facial muscles and weakness at the knees to total collapse.
Laughter, anger, excitement and fear can all cause reactions, but for Mrs Wallace her trigger is surprise.
Simple things like her phone ringing, bumping into an old friend and letters coming through the door have all made her collapse - at its worst up to 20 times a day.
Her extreme form of the condition means she loses control of all her muscles and is paralysed for several minutes. Although she can hear everything, she cannot see.
Mrs Wallace from Liverpool, said: 'It started off with a very small feeling of falling whenever I laughed at something, and by the end of the week when someone at work told a funny story, I just lost muscle control and fell onto the floor.
'It's developed from laughter to shock and surprise. I can collapse just because my mobile rings when I'm holding it.
'I was shopping in the supermarket a couple of months ago when I bumped into an old friend I hadn't seen for about five years.
'It was so unexpected that I collapsed. It's really embarrassing.
'With cataplexy you can't put your arms out to break your fall. You have no control or no way stopping yourself from falling.
'I'm covered in bumps, bruises and scars from falls. I can hear people when I have an attack but I can't see or speak. It's like I'm paralysed.'
Her husband John, 35, who is a lift engineer, knows not to surprise his wife with flowers or chocolates and made sure their wedding in June last year was a low-key affair.
Mrs Wallace said: 'A surprise party would be my idea of hell. If John has something to tell me, he asks me to sit down first in case I collapse.
'If he walks into a room and I don't realise he's there, it can happen. Once, I was blow drying my hair with my back to the door. He walked in and made me jump. I fell face down onto the bed.
'John is very good. He always tries to catch me when I fall.'
Her symptoms started in February last year, and after her first attack she went to her local accident and emergency department fearing she had suffered a stroke.
Doctors there suggested she see a neurologist, who carried out tests, including a brain scan, before referring her to a specialist sleep clinic at James Cook University Hospital in Middlesbrough.
It was there Mrs Wallace was diagnosed with cataplexy and narcolepsy, which causes excessive daytime sleepiness.
Her condition means she has had to give up her driving licence and her job as a receptionist at a dental practice.
She said: 'I kept falling asleep on the phone and making mistakes because of the tiredness. It was causing a lot of problems so I had to leave.
'Work were very good and patient, but it wasn't working out to anyone's benefit'
Last Christmas, the attacks became so severe Mrs Wallace was scared to leave the house on her own and she would use a wheelchair in public.
She wasn't able to cook or have a bath on her own in case she had a cataplectic attack.
She had to stop exercising because it was too dangerous, causing her to put on more than two stone.
With medication, her condition has improved and she has started doing voluntary work with the hope of getting a part-time job next year.
Mrs Wallace said: 'A few months ago, I wouldn't have thought about the future, but I'm feeling more positive.
'When my condition was at its worst, I spent so much time indoors. I got bored of watching television so I started reading a lot of books.
'It's made me realise I want to be a writer, and now I have my days free to try and make that happen.'
Dr Paul Reading, consultant neurologist at James Cook University Hospital, Middlesbrough, and president of the British Sleep Society, said: 'People with narcolepsy lack a chemical in their brain that regulates sleep, without which they cannot stay awake for more than a couple of hours or so.
'Cataplexy is found only in people suffering from narcolepsy.
'It is triggered by intense emotion, particularly laughter or surprise, as with Caitlin, but occasionally anger or frustration.
'I have a patient who has a cataplectic attack whenever he gets a good shot while playing golf.
'Cataplexy can be treated with anti-depressants, not because the sufferer is depressed but because these drugs create a chemical state in the brain that inhibits cataplexy.'
story from www.dailymail.co.uk/
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