Laughing is no joke for Claire Scott—every time she gets the giggles she falls asleep.

The mother-of-two has a rare sleeping disorder called cataplexy, in which feelings of emotion can trigger a weakening in the muscles.

It has made her collapse up to 50 times a day since childhood. Doctors at one point feared she had a heart condition and fitted a pacemaker.

Scott, 24, once fell asleep 25 times during a Christmas lunch.

Anti-depressants have improved the condition but she recently had an attack after laughing at a joke told by her five-year-old daughter Ebony.

"I burst out laughing. The next thing I knew my husband David was picking me up off the kitchen floor. It can be really embarrassing," said the accounts clerk from New Jersey.

Cataplexy attacks last seconds to several minutes, during which victims can hear but not see.

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