When asked if researchers ever considered studying the technicians, Huynh quips, "They should."

Technicians' schedules must be unpredictable because the rooms are completely "time-free environments," without television, radio, clocks or windows. Subjects stay in them for the duration of the study, linked only to the outside world by the technicians.

All staff are carefully trained not to provide inadvertent time cues to the subjects, since any apprehension by a subject of the actual time could ruin a study.

"There could be three different times of day in three different rooms, plus the fourth, which is the outside time for the technicians," says Jayne. "Someone might be eating breakfast, someone else might be having lunch, while another person is getting ready to go to bed."

In the event that a technician inadvertently leaves a document in a subject's room, all paperwork is labelled with a "lab time" that disguises the actual time and does not rely on a.m. and p.m. distinctions.

To illustrate just how precarious the time situation can be, Jayne says that in the past, construction on floors below the lab has caused problems. Since construction work is usually scheduled for the daytime, a subject could easily realize that his "bedtime" is really in the middle of the day.

Huynh says that in one type of procedure used in experiments, called a constant routine, a subject may be required to remain in bed for 40 hours or more while sitting up and staying awake.

According to Huynh, who had to make sure the subjects were always awake, the researchers constantly monitor the performance and metabolic status of the subjects during the study.

"Performance tests are a math arithmetic test, at least once an hour...Most subjects, we collect urine samples from. We tested for blood levels of cortisol and melatonin...during a constant routine we take blood more than once an hour," he says.

Moreover, TV monitors in the control rooms keep track of each subject unless he is in the bathroom. And a rectal temperature probe takes a new temperature reading every second, which allows the subject's core body temperature rhythm to be plotted continuously on a computer screen.

Blood is drawn intravenously through a tube stretching across the room through an opening in the wall, which can be attached to a subject's arm for up to a week. A technician can therefore draw blood regularly without disturbing the subject, even when he or she is asleep.

Finally, scalp electrodes monitor brain activity through electroencephalograms (EEG's), which can track periods of REM and non-REM sleep.

All of the monitoring and careful control make the circadian rhythm and sleep studies expensive--averaging about $3,500 per day per subject, according to Jayne.

A college student would earn about $1,000 to stay at the lab for 11 days. An elderly person would earn more, and a blind person would earn the most. The lab advertises for males and females of ages 18-30, elderly people of ages 65-85, and blind people.

Before accepting a willing, needy student, however, the lab insists on a rigorous screening process that takes about a month to complete. Among the criteria: the person cannot have crossed more than three time zones in the past six months, and the person must have been drug-free for years and must not have smoked or had an alcoholic drink in the last month.

In addition to psychological and physical exams, the subject must agree to certain conditions, which Jayne admits are daunting--especially for college students. During the three weeks prior to the entering the lab, a subject must refrain from having caffeine and must agree to go to bed and wake up within half an hour of the same time.