Triggered by a chuckle
A rare symptom of narcolepsy can strike every time the patient experiences a strong emotion, such as laughter, fear or anger
Laughter, joy and surprise are, for most of us, a happy part of life.
But for scientist Claire Allen, they can trigger an extraordinary reaction, in which she falls into a trance-like state, unable to see or move. A good chuckle is, unfortunately, the strongest trigger. But she also reacts to everyday feelings such as fear, anger, joy or surprise.
Dr Allen has a rare symptom of narcolepsy, which strikes during such simple scenarios as finding a chair has unexpectedly been moved, visiting family or shopping.
Even being greeted by someone in the street can cause problems. She once fell off her bike when a friend shouted to her.
Without treatment, she can suffer up to 100 episodes every day, each lasting between 30 seconds and five minutes.
"The attacks are caused by any emotional surprise or shock, but laughter is definitely the strongest trigger," said Dr Allen, 35, from Cambridge.
"The first symptom was my head nodding like a child trying to stay awake and after six months, I was collapsing.
"A few years ago, I stopped all my medication for a trial and discovered the true extent of my symptoms — about 100 collapses a day.
"They happen more often during social contact, as I'm more self-conscious. There is no pain but my speech will go, followed by my vision. Then my body will crumple.
"It doesn't feel any different to being awake, except that I can't see or move. It is very odd for people to see me go down and then come around and be absolutely fine."
Dr Allen first had symptoms in 2004. She started having sleep problems, waking up almost 30 times a night. Later, she had muscle weakness and then full collapses.
Dr Allen was diagnosed with cataplexy, or sudden loss of muscle tone, in 2005. But now she enjoys a more normal life, after taking a new drug, Xyrem, which has cut the attacks to a few each month.
It puts her into a deep sleep for three and a half hours at a time. She takes two doses each night to get a full seven hours' rest.
"For the past five years, I hadn't slept for more than an hour at a time, so to sleep for more than three hours was incredible. Now I am much better at getting plenty of rest to cut down on the cataplexic attacks," she said.
