Severe nightly episodes of interrupted breathing during sleep - commonly known as sleep apnea - double the risk of death for middle-age men, according to a new study being called the largest ever conducted on the disorder.
Even men with moderate sleep apnea - anywhere from 15 to 30 instances of oxygen deprivation per hour - appear to be 45 percent more likely to die from any cause than those who have no nighttime breathing problems.
As many as one in four men is believed to suffer from sleep apnea, researchers said, and many with less severe apnea may not even know they have it, even though it can dangerously decrease the oxygen in their bloodstream. Sleep apnea - typically characterized by loud snoring - is believed to be a growing problem, since it is often linked to obesity, which has become an epidemic in the United States. Women also are affected by the disorder, but to a lesser degree.
"This is a bad disorder that not only affects your lifestyle in the short term, but your life span in the long term as well," said Dr. David Schulman, director of the sleep laboratory at Emory University Hospital in Atlanta, who was not involved in the study. "People with sleep apnea today are more likely to die tomorrow."
The study, led by Johns Hopkins pulmonologist Dr. Naresh M. Punjabi, is being published online today in the Public Library of Science, Medicine. Small studies and anecdotal reports have long hinted at the connection between sleep problems and death, especially from heart disease, but this is the first large research study to make the link.
This study, part of the Sleep Heart Health Study, involved 6,441 men and women between the ages of 40 and 70. They have been followed for more than eight years. Some had sleep apnea; some did not. Many identified themselves as snorers - a major symptom of the disorder. More than 1,000 participants died since the study began.
Men with apnea were more likely to die regardless of age, gender, race, weight or whether they were a current or former smoker, or had other medical conditions such as high blood pressure, heart disease or diabetes, the study found.
Punjabi said the study shows that the majority of deaths aren't the result of the daytime drowsiness that is a hallmark of sleep apnea, the result of night after night of interrupted sleep.
Losing oxygen A major culprit appears to be repeated episodes of apnea and the resulting oxygen deprivation, during which blood oxygen levels drop below 90 percent. If the heart doesn't get enough oxygen, it doesn't pump very well. As few as 11 minutes a night spent essentially holding one's breath - 2 percent of an average night's sleep of seven hours - caused the risk of death to double, Punjabi found.
"We all know that breathing's very important to our health, but because we're asleep and there's no pain, the difficulty in breathing while we sleep is not something [doctors] observe ... in a routine office visit," said Michael Twery, director of the National Institutes of Health's National Center on Sleep Disorders Research. "It's one of those hidden conditions."
Sleep apnea occurs when the upper airway is intermittently narrowed during sleep, causing breathing to be difficult or completely blocked.
The health risks appear to accumulate over many years. "It's a chronic exposure," he said. "One night's exposure in itself is not a health risk. ... It happens hundreds of times a night and it goes on for decades."
Along with so many men, about one in 10 women are believed to have sleep apnea. There were too few women in the study to draw any conclusions about apnea and death, but Twery said women also appear to be at risk. He said more needs to be known about women and apnea. There are questions, for example, about snoring during pregnancy and whether it affects the health of the mother and the developing fetus.
"It's underdiagnosed," Punjabi said. "Many physicians are unaware of this disorder. ... Patients have to know what they're suffering from."
Own snoring wakes him up Jim Cappuccino, a 49-year-old retired police officer who develops and sells medical equipment, has been snoring for more than a decade. Loudly. The Baltimore resident - who at 5 feet 10 weighs 256 pounds - recently learned he has sleep apnea, though he wasn't all that surprised. His own snoring often woke him up.
"Some nights I felt I was actually not asleep," he said. "You wake up and you're as bone-tired as when you went to bed."
Of his six siblings, four are doctors, who have long pushed him to take better care of himself and to get control over his roller-coaster weight. "It's time I face facts," Cappuccino said. "I'd like to see my [college junior] daughter graduate from college and law school."
Now, as part of a different Hopkins study, he is using a Continuous Positive Airway Pressure (CPAP) machine, a mask worn at night that pushes air through the airway passage at a pressure high enough to keep it open during sleep. After two months, he already feels better.
Schulman said the public began to pay attention to the breathing disorder after Hall of Fame football player Reggie White's death five years ago was attributed to undiagnosed sleep apnea. The message started getting out, he said: "If you snore, go see your doctor."
Apnea in the air When it makes headlines, the stories about sleep apnea are rarely good. This month, National Transportation Safety Board officials said the reason a plane in 2008 overflew a Hawaii airport was because the pilots fell asleep and the captain suffered from undiagnosed sleep apnea. The NTSB is calling for pilots to be screened for sleep apnea.
Schulman said treating apnea - through CPAP machines or by losing weight - might prevent deaths, though more research needs to be done.
Sleep apnea is diagnosed through a visit to a sleep clinic, something not everyone is willing or able to do.
"When we get people in the clinic, they're usually here because they're sleepy," Schulman said. "Often, folks will take treatments because they like the way it makes them feel."
But not everyone with apnea feels poorly. Some with more moderate, but still potentially dangerous, night breathing problems don't know there is anything wrong.
"There are some people with apnea who don't feel bad," he said.
With that group, when the doctor suggests the bulky CPAP machine, "that's a much harder sell," Schulman said.
By the numbers:
Middle-age people with severe apnea were:
46 percent more likely to die of any cause.
Middle-age people with moderate apnea were
17 percent more likely to die of any cause.
About 1 in 4 men and 1 in 10 women suffer from sleep apnea
Breathing problems for as little as 11 minutes a night cause the risk of death to double