The patient is 65 years old and he stops breathing every 30 to 40 seconds throughout the night, a condition known as "sleep apnea". In a case as severe as this the victim awakes unrested and feels the irresistible need to sleep during the day.

Tonight researchers will carefully monitor and record every function of his body having to do with sleeping and breathing. He has been transferred from Harvard affiliated Massachusetts Eye and Ear Infirmary to the Sleep Disorders Clinic and Laboratory in nearby Harvard affiliated Massachusetts General Hospital.

At 11 p.m. two hours after the usual entry time the patient is admitted. He has electrodes and other devices strapped and taped to his head and upper body. But like most apnea patients, he is so tired that not even these prevent his almost immediate sleep.

Also almost immediately, the patient stops breathing. The readout of his vital signs, led by in formation from the devices on his body into 17 sapphire tipped pens sliding back and forth on a continuously moving strip of paper, instantly reflects the change.

The line showing airflow through mouth and both nostrils drops to nothing. The heartbeat reading becomes erratic. Movement of chin and chest are spasmodic as the patient struggles to draw in air. Eye movement changes and nine channels of brain wave recordings take on the appearance of waking brain activity in the thin blue lines.

Finally, after about 10 seconds the patient takes a breath. The functions return to their previous appearances. A television monitor, displaying the darkened bedroom for those outside watching the readout, reveals that the man is once again breathing fairly normally.

Then 30 seconds later, it happens again About 100 times an hour from 11 p.m. until 6 or 6.30 a.m. the patient will temporarily stop breathing. Chances are he will hardly remember it, but each time he wakes up briefly. He will remain fatigued all day.

In the next room, also hooked up to a variety of monitors and a recording device, is a 30-year old woman who suspects that she has insomnia. She arrived at about 9 p.m. the usual hour for patients to enter the lab for overnight stays, and her vital signs will be recorded until 6 a.m. as well. She is an outpatient, in the clinic just for the night, and unlike the sleep apnea patient, she requires no supervision from the lab's two-man team.

The woman's readout is similar to the man's though several of the functions being monitored are different. Whenever she turns over or even moves more than slightly, the readout goes haywire as the connecting wires vibrate. The pens shoot back and forth so quickly that the resulting pattern is almost solid black. This patient can be left alone, for her diagnosis will be determined during the day by reviewing the information on the printout. The lab team will devote most of their attention to the man.

"He's trying to breathe, but he can't--it's as if someone is strangling him," explains Dr. John W. Stakes III, instructor in neurology and supervisor of the nightly tests. Other doctors handle the lab in the daylight hours, but on Monday and Tuesday nights, Stakes is in charge.

Aside from the severity of his case, Stakes adds, tonight's patient is typical of apnea sufferers. He is in late middle age, moderately obese, with a short neck, and male. Most apnea victims are, and their wives bring them in to this clinic or others like it complaining that while their spouse has always snored, recently they have noticed that he seems to stop breathing.

Stakes says that this patient has the worst case of apnea he has seen in "quite a while," and the lab technician. Margaret A. McMahon, agrees. McMahon monitors the sleeping patients, making sure that the readings are of the highest available quality.

This evening, the chest movement monitor has been strapped on the man incorrectly so that the graph is not as clear as it might be. Shortly after midnight, McMahon goes into the room followed by Stakes, to adjust the strap around the patient's chest. It needs to be moved further down his body because he appears to be breathing less with his chest than with his abdomen.

McMahon will spend the rest of the night making sure the patient is still wearing all of the mechanical devices he should be and recording his blood's oxygen saturation reading Displayed on a digital readout, the oxygen saturation measures how efficiently the body is inhaling and distributing oxygen. A normal saturation is around 95 to 97, but this patient's seldom exceeds 80, and drops as low as the low 40s during apnea episodes McMahon noting the reading every few seconds, will mark it in felt-tip pen as the paper rolls along.

Sleep apnea victims are "the most difficult patients to monitor." McMahon says, jotting numbers constantly. She seems unperturbed by the continual struggle going on in the darkened cubicle. The only sounds are the scratching of pens on paper and the occasional bushed voices of the doctor and the technician.