"The descriptions of my snoring went from something like a growling bear to a machine that was going to knock down the house," he said. When he and his son went camping in southern Utah last year, his son asked him to sleep in the truck.

He felt bone-tired during the day, what he describes as "30 years struggling against this weariness that you feel perpetually. No alertness. No get-up-and-go."

Finally, Chapman spent a night at Torrance Memorial, plugged into the polysomnograph. The test results were startling: He was holding his breath as many as 57 times an hour, each time for 10 to 40 seconds. He would wake repeatedly as he held his breath, meaning that he unknowingly was sleeping only four or five hours a night.

A federal report concluded that while 60 million Americans suffer from apnea, narcolepsy and other chronic sleep problems, the majority are undiagnosed and untreated. Despite its pervasiveness and impact upon the society, sleep-related problems are not recognized as a public health issue.

The most common and severe form, called obstructive sleep apnea, features extremely loud snoring interrupted by pauses and gasps. Breathing stops for 10 seconds or longer, sometimes dozens or even hundreds of times each night.

Most frequently, the airway becomes blocked during sleep due to excessive relaxation of throat muscles. In children, sleep apnea is often the result of enlarged tonsils and adenoids.

People with sleep apnea may show signs of anxiety, depression, irritability, forgetfulness and fatigue during the day. Recent studies have found that sleep apnea sufferers have two to five times as many automobile accidents as people in the general population.

Treatment includes weight reduction (most people with severe sleep apnea are overweight); avoiding alcohol within two hours of bedtime and sleeping drugs; surgery to remove excess tissue at the back of the throat or enlarged tonsils and adenoids; use of a special mask that improves flow of air through nasal passages.

Undergoing surgery or sleeping with a mask clamped to your face may seem like extreme measures just to silence snoring. But if you have sleep apnea, those treatments could save your life.

As awareness of apnea mounts, suspected sufferers are spending their nights under an infrared camera's watchful eye in hundreds of so-called "sleep labs" across America, sensors dotting their skin and scalp.

Eleven o'clock is "lights out." At 11:02 sharp, Navarro yawns. A needle swings wildly on a monitor humming softly in the next room. At 11:10 p.m., Navarro turns onto his left side, and a half-dozen needles jerk in response.

This night will be like no other for Navarro, a 32-year-old computer programmer. For the next seven hours, his every breath, movement and heartbeat will be recorded as he spends the night in a sleep disorders laboratory.

He is here because doctors think he suffers from sleep apnea, a disorder marked by loud snoring and interrupted breathing. Once considered relatively obscure, sleep apnea is stirring increased concern among physicians because it can cause severe daytime fatigue, high blood pressure, stroke and heart problems; serious cases can be life-threatening.

A study published in the New England Journal of Medicine reported that sleep apnea is more common than once believed. The study found that 9% of women and 24% of men had sleep-disordered breathing; 2% of women and 4% of men in the middle-aged work force met the criteria for sleep apnea. That would make undiagnosed sleep apnea a major public health burden.

Depending on the severity of the apnea, treatment can include use of a night time face mask or even surgery. There's a less high-tech approach for those who snore or suffer apnea only while on their backs: sewing a tennis ball in the back of their pajamas tops so they will sleep on their sides instead.

Not surprisingly, roommates and spouses are often the first to spot potential apnea victims. Navarro is a longtime snorer; he can remember his college roommates waking him to request that he tone it down. His wife, Christine, grew worried when she noticed that he sometimes stopped breathing briefly during the night. She learned about sleep apnea from her doctor and urged her husband to get tested.

A video screen shows Navarro dozing peacefully. Pink computer paper moves steadily through the polysomnograph, a machine with 12 needles that records everything from his eye movements to heart contractions.

All night, monitors will record the needles? black tracks, paying special attention to those measuring Navarro's breathing. Sleep apnea victims have been known to stop breathing hundreds of times each night.