The young, well-dressed woman was walking along a crowded downtown sidewalk at lunch hour when, without warning, she tumbled to the pavement and lay there in a heap, apparently unconscious.

A passerby called a D.C. Fire Department ambulance, which arrived within minutes. As a small crowd huddled around the fallen woman, two medical technicians came hustling over to see what the trouble was.

One of the technicians bent over the woman to feel for a pulse. But just as he was about to start counting, he recognized her. His mouth curled into a knowing, annoyed smirk.

"Hey, Marty, forget it," he called to his partner. "It's The Collapser again."

For the last several months, The Collapser has been crumpling into a heap on sidewalks all over the city -- at least once a day, sometimes more often. Each time she falls, a bystander calls the fire department, which sends an ambulance. But each time, that ambulance has proven unnecessary, because The Collapser has not suffered a heart attack or a seizure. She has merely gone to sleep -- because of a condition called narcolepsy.

Narcolepsy is a fairly common neurological ailment. Narcoleptics fall deeply asleep in seconds, anywhere, regardless of what else they may have been doing when the urge to sleep descends. After a few minutes, narcoleptics usually wake up and resume their business. Often, they're unaware that they've fallen asleep or fallen down.

In the case of The Collapser, she's usually getting to her feet and brushing off her clothes at about the time the ambulance arrives. It's a frustrating and costly exercise for the ambulance service, which spends $45.92 of taxpayers' money each time it makes a needless run to The Collapser's side. And it's a bewildering spectacle to bystanders, who think The Collapser must be a drunk, a malingerer or a practical joker, and who wonder why all that money and manpower has to go down the drain each time she "goes into her act."

One obvious option would be for the ambulance service to refuse to show up when a "Collapser call" comes in. Two things wrong with that: The dispatcher on the fire department switchboard has no way of knowing that the reported "unconscious person" is The Collapser. And The Collapser may actually need an ambulance because she may have injured herself as she fell. A serious gash, a broken bone, a concussion -- all are more than remote possibilities.

But in several months of falls, all over the city, at all times of day, The Collapser hasn't suffered any of those injuries, or any others. So, Fire Department officials are under pressure to save a few bucks by ignoring her the next time she takes a tumble. For now, however, they're resisting.

"If she collapses and says she has a legitimate condition, that is good enough for us," said Ray Alfred, chief of public affairs.

"She has a need for our service at the time she calls, and we have scads of people who do that," added Thomas McCaffrey, a battalion chief who's assistant director of operations. " . . . She is not abusing our service."

"One option might be for her to stay at home. But we really can't suggest that," said Dr. Victoria Countee, the fire department's medical director. The Collapser "is a young woman," Dr. Countee said, "and we can't confine her" just because her ailment is inconvenient to ambulance drivers. "If she calls for an ambulance, she will still get one," said Dr. Countee. "That's our job."

But isn't there a better way? And doesn't the case of The Collapser point up the need to modify the city's ambulance service somewhat? Tomorrow, some suggestions as to how that might be done.