When the body is exposed to cold, the nervous system constricts blood flow to hands and feet to retain heat. When the temperature of the extremities reaches dangerously low levels, the nervous system in effect throws a switch that dilates blood vessels and restores full circulation, Dr. Hamlet said.

But Raynaud's sufferers do not regain circulation because blood vessels leading to their hands do not dilate as they should. Researchers have been unable to determine what causes the condition, Dr. Hamlet said.

It is unclear how many people have Raynaud's, which occurs predominantly among women, affecting perhaps as many as 10 percent of them, Dr. Hamlet said. Many victims are not aware they have the disease because they think their body's response to the cold is normal, he said.

A procedure originally devised a decade ago by an Army doctor at an laboratory in Alaska to treat the disease has been refined by reasearchers at the Army laboratories here and now is being used more and more by civilian physicians, Dr. Hamlet said. Warm and Cold Water

Three to six times a day, every other day, Raynaud's sufferers undergo a treatment in which they first sit indoors with their hands submerged in warm water and then are put in a cold environment, exposed to the cold except for their hands, which are submerged in an ice chest filled with warm water.