For most Harvard students, earning money while sleeping seems like a dream come true.

At Harvard-affiliated Brigham and Women's Hospital, subjects are doing just that.

Twenty-four hours a day, seven days a week, participants in studies conducted by the hospital's Laboratory for Circadian and Sleep Disorders Medicine are busy contributing to the study of circadian rhythms, the science dealing with the operation of one's "biological clock."

Participating in a study actually involves a considerable amount of tolerance and perseverance. Gerald A. Jayne, chief research technician at the laboratory, estimates that the lab receives about 200 phone calls per week from people interested in becoming subjects. "Around 90 percent of people, after hearing what's involved, don't want to do it," he says.

Subjects must typically stay from four days to six weeks in one of the lab's eight suites, which are spacious, minimally furnished and painted completely white.

Ceilings are completely covered by panels of bright fluorescent lights, which can provide lighting levels ranging from dim to extremely bright.

The lights, for example, can be used to induce an artificial jet lag effect in a subject. Researchers can vary the duration and timing of the light and dark periods, as well as the intensity of each light exposure.

To reset a subject's biological clock according to light exposure, in a process called "entrainment," the lights in the suite can be raised to an intensity of 10,000 lux, which is about the intensity of sunlight at dawn or dusk.

Thien T. Huynh '97, a former summer work-study technician at the lab, says that in one particular 11-day study the subject had to stare at a picture of an eye on the wall for 10 minutes, rest for five to 10 minutes, and then look at the picture again for 10 minutes.

"It's just a place to focus on; they had bright light on the whole time. When they're staring at the eye they get more light, and they get less when looking at the floor. There's a light meter that measures how much light they're getting at each point," Huynh says.

Findings that have emerged from research on the ability of light to reset the internal clock has improved the lives of many shift workers. Monica L. Stemmle '96 was involved in shift work research during the summer of 1994. "I participated in a five-year study on whether properly timed bright light could improve shift workers' performance."

Ironically, according to Jayne, the worst part of the technician's job is a rotating schedule. Since technicians wake patients up and bring them meals, a regular staff schedule would give subjects time cues," or clues about what the actual time is rather than what time they are subjectively experiencing.

To ensure irregular staff rotations, the technicians work according to an eight-week schedule so complex that "technicians can't even figure it out," says Jayne.

Jayne also noted that Dr. Charles A. Czeisler '74, director of the lab, has found that shift workers suffer more from rapid rotations, as opposed to fixed shifts or shifts that rotate every few weeks. Jayne jokes, however, that in the interest of science "[Czeisler] doesn't practice what he preaches. For easier adjusting, the schedule always rotates up--for example, the shifts could run day, day, evening evening, night, followed by one of two days off.

Huynh says, "I felt like I was a subject myself because I was working such weird hours. One week I would be working five-hour nights, another week the day shifts, and another week the night shifts."