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 target="_blank">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.