Until a few months ago, Harold Flygare couldn't sit down without falling asleep. If he got comfortable for a minute during the day, to talk to a friend or read a book, he'd doze off. "I couldn't even watch a game on TV," he says. "It was rough."

Flygare had plenty of health problems: A hiatal hernia. High blood pressure. Pains that seemed like heart problems and for which he had many inconclusive tests.None of his problems seemed to fully explain his sleepiness and lack of energy, though. "I got to the point where I couldn't walk across the room without stopping to rest," he says.

Flygare knew he snored, his wife had mentioned it to him on more than one occasion. And he had heard that people who snore loudly and consistently may have sleep apnea.

"I thought someone had just invented another word for snoring," he says. He never linked his daytime fatigue to his nighttime noises until a neighbor of his, in Ogden, was diagnosed as having sleep apnea.

Then Flygare learned exactly how that physical condition causes people to be too sleepy in the daytime.

When people have apnea their sleep is constantly interrupted. Doctors don't know exactly why some people's throats get obstructed when they sleep. Some have a throat too small for the base of their tongue. In others, for some reason the throat muscles relax too much when they sleep. The more a person weighs the worse the problem is.

At any rate, when people have sleep apnea their airway collapses a bit when they inhale. They don't get enough oxygen in their blood. Carbon dioxide builds. Their brain sends out a little startle alarm and they rouse themselves - snoring, gasping.

This cycle repeats hundreds of times each night. People with sleep apnea don't sleep soundly, no matter how many hours they sleep or how often they doze during the day.

At the University of Utah Health Sciences sleep disorder lab, Harold Flygare learned he does have sleep apnea. Now he straps himself to a little machine called a CPAP (continuous positive airway pressure) before he goes to bed each night. The CPAP forces air down his throat. He gets oxygen; he sleeps deeply. Harold Flygare feels much better.

"I feel so good, I went swimming yesterday. I'm starting to work in the yard a little bit. I can do most things now."

Flygare is going to be awake for the World Series this year, which pleases him greatly. But he wants to let others know that missing out on TV is the most minor danger of letting sleep apnea go undiagnosed.

"The important message is this: Sleep apnea is often associated with high blood pressure, heart disease or strokes," says Dr. Robert Farney. "It's an association," he repeats. No one has proven that lack of oxygen night after night is fatal. But Farney doesn't believe sleep apnea does your organs any good.

Farney runs the Intermountain Sleep Disorders Center at LDS Hospital. Since 1973 he has seen several thousand people for a complete clinical evaluation and then, if warranted, a night in the lab.

The clinical evaluation is all-important, he stresses. So often sleep disturbances are only part of a patient's health problems, problems that may include thyroid disorders, underlying lung dis-ease or heart disease.

Anyone can have sleep apnea. Farney has seen patients as young as 10 and many in their 70s. There is however a certain type of person who has it more often. Men and post-menopausal women who are obese are prime candidates for apnea. The extra weight on neck and chest may restrict a person's breathing only slightly - but that little difference may be too much.

Other physical characteristics that point to breathing difficulties at night include a small chin, large tonsils or palate, and a short neck. Drinking alcohol or sleeping on your back make matters worse, Farney adds.

At the sleep disorders lab patients spend the night in a big pine bed covered with a bright bedspread - and a bunch of sensors and wires.

Do they ever have trouble falling asleep, knowing that a technician and several machines are busily monitoring their heart, their brain, their eye movements - their every breath? "No," says Dr. Farney. "These people are tired."

The test results come as a stack of computer printouts three inches thick. From this Farney can recommend treatment. In rare cases the breathing problem could be solved by something as simple as sewing tennis balls on your p.j.'s to prevent you from sleeping on your back.

Usually sleep apnea is more persistent. It used to be solved by a tracheotomy or another operation to open the airway - a process Farney calls a "glorified tonsillectomy."

Tracheotomies are awfully drastic, and the tonsillectomies sometimes stopped the snoring without measurably increasing the amount of oxygen patients received.

All in all, Farney welcomes the invention of the CPAP machine. He's been giving the device (which looks like a bread box with a vacuum cleaner hose attached to it) to patients for three years.

One of Farney's CPAP patients, Joe Libin, explains that the machine is far from comfortable - but that he's just noticed the discomfort lately. "I've been on it since April," Libin says, "and I needed it so desperately at first I didn't even notice it."

Libin's been losing weight and generally taking better care of his health. He finds he's gone from eight naps a day to none and feels great. And the nose piece on the CPAP machine is starting to bother him. He plans to get back into the sleep lab to have Farney tell him if he can do without the machine.

Farney says most patients can go off the CPAP in a year or so, if they lose weight and are breathing better. Another option for patients is a dental device that holds the chin out and keeps the airway from flopping closed.

But, Farney stresses, deciding whether a person has sleep apnea and what should be done about it is a complicated process that few doctors have much experience with.

"If you only test for apnea and not for other physical problems, you are blinding yourself," he says. Advances in treatment are coming fast in this misunderstood disorder that has been with us since antiquity, says Farney.

"Until very recently we thought people who have sleep apnea were just very very lazy," he says.