BALTIMORE — Nightly bouts of interrupted, oxygen-deprived sleep raise the chances of dying in middle-aged to elderly people by as much as 46 percent in the most severe cases, according to a landmark study on sleep apnea.
Even in people with moderate forms of the sleeping disorder, with anywhere from 15 to 30 episodes of interrupted breathing during each hour of supposed rest, the risk of death jumps 17 percent.
As part of the Sleep Heart Health Study sponsored by the National Heart, Lung and Blood Institute (part of the National Institutes of Health), lung experts at Johns Hopkins and six other U.S. medical centers studied 6,441 men and women between ages 40 and 70 with mild to severe forms of sleep apnea or none at all. Some 1,047 deaths occurred among study participants since the clinical investigation began.
The study is believed to be the largest ever conducted into sleep and related illnesses, with the latest report taking more than a decade to complete.
Reported in the Public Library of Science, Medicine, researchers found that as little as 11 minutes a night — just 2 percent of an average night's sleep of seven hours — spent in severe sleep apnea and subsequent oxygen deprivation, in which blood oxygen levels drop below 90 percent, doubled the death rate in men.
Researchers said they suspect further study could bear the same results for women.
It is estimated that 24 percent of American men and 9 percent of women have irregular breathing patterns during sleep, with four in five unaware that they have a problem.
"Such an increased risk of death warrants screening for sleep apnea as part of routine health care, in which all physicians should inquire about patients' sleeping habits," according to pulmonologist and principal investigator Naresh Punjabi, M.D., Ph.D., an associate professor at the Johns Hopkins University School of Medicine. CPAP therapy is key, he said, adding that low blood oxygen levels during sleep are the single biggest predictor of death in people with sleep disorders.
Other investigators involved in the report included researchers at Boston University, University of Arizona, University of Pittsburgh, New York University, Case Western Reserve University and University of Southern California.