Cataplexy: A debilitating medical condition in which a person suddenly feels weak and collapses at moments of strong emotion such as laughter, anger, fear or surprise. In so collapsing, people with Cataplexy may injure themselves.
Laughter and other emotions trigger a reflex in persons that can bring many of the muscles of the body to the point of collapse. The phenomenon can be measured by sending electric signals through the muscles and gauging their response. In Cataplexy, what is known as the H-reflex, a neurological pathway that causes muscle contractions, virtually disappears.
Cataplexy often affects people who have narcolepsy, a disorder in which there is great difficulty remaining awake during the daytime.
The word "cataplexy" comes from the Greek "kata" meaning "down" + "plexis" meaning a stroke or seizure = a falling-down seizure.  This information was found on medicine. net.......
                                                         My Days With Cataplexy,
I stand looking out into the distance over the water.
I lean upon the tree for support knowing that I have overdone it.
I sit upon the base of a fallen tree. my cane close at hand.
for when I am very tired, I need that darn thing to stand.
I was startled by a biker as he rode upon the trail behind where I was sitting.
He had said hello, my head slumped down, I had a Cataplexy spell.
Thank God that I was sitting or I could have fallen to the ground.
The passerby had probably thought me rude,
you see I can not speak or talk or even move.
In about two minutes I am back, just more tired than before.
I put both hands on side my head and look into my lap.
I know the only thing to get me through the day,
Is too lay down and have a nap.
Even though I have times of anger.
where I want to do more,
I am tired of spilling dishes, and food falling on the floor.
I look over to where the truck is parked,
I must make my way, one foot in front of the other,
The feet seem to get heavier and heavier as I continue on my way.
Come on dear Lord, please just help me get to the truck.
This time I knew that I would need some luck
Walking towards me I saw my husband coming over the hill.
I knew he would be wondering why I had not stayed still.
He gently put his hand in mine, and offered me support,
He told me of what he had seen while he was out walking.
We made our way slowly the rest of the way,
and he helped me in the truck.
He said that I was really tired,
and I commented that I could not remember when I was so exhausted.
We laughed, because I say that everyday,
And as we laughed my head slumped forward
and I had another Cataplexy spell.
I am not complaining,
I am just trying to explain
what a normal day is for me.
I am careful when I hold a child and always sit down, 
I don't go on escalators, or swim, or go where the senses can be overstimulated.
No bright lights, no comedy clubs, no boats, no driving, even have to be careful
when I am cooking, or having a bath, or walking on the stairs. or talking to my friends, family
and neighbors, for you just never know what they will say, so I have chairs all over my yard,
so that I can be somewhat prepared for my day.
Note to self...there are always people much sicker than I  and though we all try to appear as if we are okay,
Be kind, don't be scared to ask questions, let them know your there for them.
If some of the fear and anger can be replaced by educating others,
then it is best just to be there. 
sometimes when people get sick, healthy people don't know what to say.
I don't think it is lack of interest, I think it can bring out some very 
uncomfortable and awkward moments.
Because my life has changed so drastically, and our lifestyle has changed,
alot of friends have stayed away,
Maybe it is because they can not stand to see me different.
I am okay with it, it is not like we can pick or choose .
I hope this has given you a little more insight
as to what Cataplexy is.
It is a symptom of Narcolepsy.
My cataplexy is considered very severe.
Medicine helps to keep it somewhat under control,
you just never know when an emotion will trigger it..
On that note, I am off to sleep.