At 7 a.m. last Saturday, five young men and women, volunteers in a drug study, lay sleeping in cramped, separate rooms at the National Institutes of Health clinical center in Bethesda.

Attached to their heads were wires that fed into a monitoring station down the hall, where an electroencephalograph recorded their brain waves in endless squiggly lines. On the station's frosted glass door was a yellowed clipping. "Slumberland," it said.

Suddenly, the silence was shattered by the urgent crackling of the intercom.

"Heart O.D. 3N224. . . Heart O.D. 3N224." Hospital attendants began sprinting down the long corridor, white coats flying. Sleepy-eyed volunteers, still in pajamas, stood outside their rooms as an emergency "crash team" rushed to Room 1A.

"It's Bernadette," one of the technicians whispered. "She didn't wake up."

Bernadette Gillcrist, a 23-year-old nursing student from Catholic University, was pronounced dead one hour later. Doctors who examined the electroencephalogram discovered that Gillcrist's brain waves had "gone flat" at 5:15 a.m.

Gillcrist's death in a routine study at one of the world's most prestigious medical facilities was the kind of event that touches the most deep-seated concern of anyone who has been in a hospital -- fear of the unknown.

"You just don't expect someone to die in a sleep study at a hospital," said Bill Strassberger, a 25-year-old volunteer who was sleeping across the tiny hallway from Gillcrist.

Why the quiet and studious young nurising student did not wake up that morning is still a mystery. The death initially was attributed to heart failure, but an autopsy could not confirm it, and left baffled doctors searching for clues.

The first death in 25 years of using "normal" volunteers in NIH research studies that have involved some 67,000 persons, it was likely to have a substantial impact on NIH policies.

Investigators looking into the circumstances surrounding Gillcrist's death will focus on three disturbing questions:

Why Gillcrist had lied about her medical history when applying for the program last December. Although studying for a career in medicine, she did not tell anybody that she had been hospitalized for cardiac arrest and for anorexia nervosa, an emotional disorder that other results in severe weight loss.

Vomit, frequently a sympton of anorexia, was reportedly found in Gillcrist's purse.

Why hospital officials were unable to detect her past medical problems. Gillcrist underwent a physical examination before joining the study and was found to be healthy. Later, a hospital admissions supervisor discovered that Gillcrist had been hospitalized at NIH for heart problems, but the information was never passed on to the study's director.

Why the sleep lab technician, who reportedly spoke with Gillcrist shortly before her death, did not become alarmed when the electroencephalogram went flat and did not enter the room again for two hours.

The bizarre chain of events which ended with her pre-dawn death on April 12, began last December when Bernadette Gillcrist -- who had always planned on a medical career -- walked into the sleep laboratory and volunteered for a National Institute of Mental Health study.

Notices of NIH experiments are routinely posted in Washington area colleges. Volunteers are paid by the hour, and can easily make $100 in a weekened. For the NIMH drug study, Gillcrist and the other volunteers were to receive $800.

The experiment was to monitor the effect of two drugs, ALPHAMETHYLPARATYROSINE (AMPT) and lithium, an antidepressant, on mood and sleep patterns. Researchers were trying to determine if AMPT could combat the insomnia that is a side-effect of withdrawing from lithium. although lithium is a widely-prescribed drug, AMPT is not. In fact, NIH was one of six hospital testing AMPT and the only facility combining it with another drug.

The auburn-haired, straight-a student had just made the Dean's List at Catholic University.She also had been working part-time at the NIH Cancer Institute since September.

Gillcrist was no stranger to the medical profession. "She was always talking about being a nurse or a doctor," said her 22-year-old sister Sharon last week. "We have a lot of nurses in the family." Sharon, a social worker, said her older sister Marcia is a speech patholgist. Their mother works as a medical secretary in a Chevy Chase medical center.

Raised in a strict Roman Catholic family, Bernadette attended Ursuline Academy, a private girl's school that closed several years ago. She went to Fairfield University in Connecticut, and attended Montgomery College before transferring to C.U. as a scholarship student in her sophomore year.

One classmate remembers her as "someone really good to talk to, someone with a good head on her shoulders."

The second oldest of nine children, Gillcrist may have needed the $800 for medical school tuition next year. So when the NIH staffers asked if she had ever been there before, Gillcrist lied and said she had not.

"Maybe she thought she could handle it," said Sharon Gillcrist. "It's funny, you know? The people who knew about her medical problems didn't know she was in the study."

What Bernadette Gillcrist was hiding would have made her ineligible to be a "normal" volunteer. In August 1975, at the age of 18, she suffered her first cardiac arrest. "I found her on the floor of the bathroom one morning," Sharon Gillcrist recalled. "She spent two weeks at Suburban Hospital."

A second cardiac arrest occurred in April 1976, and Gillcrist again was taken to Suburban Hospital where she lay in a coma for three days. When doctors could not determine the cause of her heart problem, she was admitted to NIH across the street.

The physicians discovered her heart ailment was due to low potassium levels. "They told her there was no damage to her heart muscle," her sister Sharon said. "Maybe she though there would be no problem. They didn't say the drug study would be dangerous."

When Gillcrist applied to the study last December a hospital staff member checked the computer and found a previous entry for a Bernadette Gillcrist. But the name in the computer had a different middle initial and a different address. It is not clear whether Bernadette herself denied that she was one and the same, or whether a hospital staffer assumed there were two separate people. But later it was leanerd that the two names had the same birth date.

By January, the admissions supervisor had telephoned someone in the sleep lab and informed them that Gillcrist was a former patient. The information reportedly was never passed on to the study's director. Dr. Chris Gillin.

By then, Gillcrist and 19 other volunteers had began taking lithium, which was the initial phase of the program.

Bill Strassberger, a 25-year old University of Maryland student who heard about the experiment during Christmas break and immediately enlisted, remembered "Nurse Bertie," as he nicknamed Gillcrist, as a cheerful and hardworking young woman.

Although there were 20 people in the program, the lab sleeps only four at a time.Strassberger met Gillcrist in early April and both were scheduled to be monitored at the sleep lab from Wednesday night, April 9, through Thursday, April 17.

On Wednesday night, Gillcrist was interviewed by a sleep lab technician and asked if she had any history of medical problems. She already had been given a complete physical examination. One of the questions was whether any family member had ever experienced any heart trouble. Gillcrist answered no, despite the fact that her father, Walter, had died in 1971 of a heart attack.

"I guess there would be no way for them to check your medical history," Strassberger said. "If you don't want them to know something, you don't tell them."

Strassberger and Gillcrist were joined by three other volunteers, a 32-year old Rockville man, a Washington law clerk and another man who was not identified. "Sure, Money was the motivation," said one volunteer. "Isn't it always."

Gillcrist was worried about an upcoming final examination and had brought her school books to the sleep lab.

All of the volunteers had been given 300 milligrams of lithium carbonate four times a day for a week. On Friday morning, each volunteer was handed four blue capsules of AMPT (which is also known by the trade name Demser) to be taken a intervals throughout the day. The entire dosage was 1,000 milligrams.

Gillcrist attended classes Friday afternoon, then took the bus to NIH, arriving at about 4:30 p.m. for a "pupilometry," an eye examination routinely given to sleep study volunteers.

Gillcrist then boarded another bus and rode to Plainview Road in Bethesda for an appointment with her psychiatrist, Dr. William Legat.

An NIH official said later that the psychiatrist had not prescribed any drugs for Gillcrist and that the nursing student did not tell her doctor she was participating in the study.

According to her sister Sharon, Bernadette was concerned about her weight and was always dieting. Anorexia nervosa usually affects young women who are obsessed with becoming thin. Bernadette Gillcrist had lost about 25 pounds in recent months.

Gillcrist returned to the clinical center at 9:30 that night, Strassberger recalled, visibily tired.

"She seemed really groggy, really out of it," he said this week. "They said that was one of the side effects of the AMPT. She said she was never so anxious to go to bed."

Friday was the first day the volunteers were given both drugs.

Gillcrist walked down the dingy hospital corridor, dotted with closets and small offices, to the soda machine where she bought a Tab. When she returned, she sat down next to Strassberger and started to doze. About 10:30, the technician hooked the wires to Gillcrist's head and she went around the corner to room 1 A to go to sleep.

"That was the last time I saw her alive," Strassberger recalled.

The rest of the volunteers were hooked up. Three slept in the lab, in separate tiny rooms. The fourth slept on the floor above, still mnitored by the same electroencephalograph.

There was one technician, a woman who reportedly had worked at the center for two months, on duty.

Bernadette Gillcrist slept soundly, according to the graph, unitl 5:15 a.m. when she made a sudden motion, such as rolling over. Then the lines on the machine went flat, signalling no brain activity. According to hospital officials, the technician went into the nursing student's room and reportedly had a brief conversation with her, making sure the wires were still hooked to the circuit.

The technician then left the room, walked 10 feet away to the monitoring room and noticed that lines registering Gillcrist's activities were still flat. Assuming the machine was broken, the technician reportedly fiddled with the dials, but did not try to arouse Gillcrist or return to her room.

"I woke up about 7 a.m.," Strassberger said. "The other volunteer from down the hall was also awake. I heard the technician ask him to help her rouse Bernadette. She said she couldn't wake her up or something. I unplugged my wires and went out ino the hall. Then the commotion started."

The emergency team worked on Gillcrist, frantically pounding on her heart, but could not revive her. In fact, officials now say, she had been dead for nearly two hours.

Strassberger went to the electoencephalogram and saw Gillcrist's printout. "You could see it," he said. "There was one big jump. Then it goes flat."

According to one NIH physician familiar with the sleep lab, the EEG machine frequently fails to work properly. "It happens every night," the physician said. "I quess nobody thought anything of it."

Medical authorities believe Gillcrist's death was caused by her previous heart ailment. The Gillcrist family, however, has hired an attorney, Gordon Forrester Jr., who said he believes the medical examiner will find she was in perfect health at the time of her death.

"If negligence can be proved, then a court action is likely," said Dr. Charles McCarthy, head of the NIH Offices for Protection from Research Risks. A final autopsy is pending further tests.

The four remaining volunteers were sent home Saturday afternoon and the sleep lab has been closed down indefinetly. Strassberger said the volunteers are shaken up. He will not be taking part in any more drug studies.

Last week NIH officials sent out letters to 600 government-funded research facilities in the country, informing them of the volunteer's death and warning them to use stricter controls on compiling medical histories, asking for written documents when ever possible. The clinical center also will check their own hospital records routinely from now on for prospective volunteer's past medical data.

Asked what might have caused her daughter's death, Bernadette's mother Marcia said. "I haven't the vaguest idea."