A new study on sleep apnea reveals there could be some hidden dangers - particularly for women who have the condition - where breathing is interrupted during sleep. Women with sleep apnea may appear healthy, but they have subtle symptoms so their sleep problem is often misdiagnosed.

Now, new research, led by the University of California Los Angeles (UCLA) School of Nursing, shows that the body's autonomic responses, which normally control blood pressure, heart rate, sweating and other basic functions, are not as strong in people with obstructive sleep apnea, and even less so in women.

Obstructive sleep apnea is a serious condition that happens when the person is asleep, sometimes hundreds of times a night. When it occurs, blood oxygen drops and eventually damages many cells of the body.

There are over 20 million adult Americans living with the condition, note the researchers, who explain that it is linked with several serious health problems and also early death.

Women are much less likely to be diagnosed with obstructive sleep apnea than men.

Lead researcher Dr. Paul Macey says:

"We now know that sleep apnea is a precursor to bigger health issues. And for women in particular, the results could be deadly."

Early detection and intervention needed

Dr. Macey and his colleagues describe their work in a recent online issue of PLOS ONE.

For their study, the team recruited 94 adult men and women, comprising 37 newly diagnosed, untreated obstructive sleep (OSA) patients and 57 healthy volunteers to act as controls.

The three groups had their heart rates measured as they went through three different physical challenges:

  • The Valsalva maneuver - where they had to breathe out hard while keeping the mouth closed
  • A hand-grip challenge - where they had to just squeeze hard with one hand
  • A cold pressor challenge - where the right foot is inserted into near-freezing water for a minute.

The team notes the main results:

"Heart rate responses showed lower amplitude, delayed onset and slower rate changes in OSA patients over healthy controls, and impairments may be more pronounced in females."

Dr. Macey adds:

"This may mean that women are more likely to develop symptoms of heart disease, as well as other consequences of poor adaptation to daily physical tasks. Early detection and treatment may be needed to protect against damage to the brain and other organs."

The team now intends to investigate if the usual treatments for OSA, such as continuous positive airway pressure (CPAP), help to improve the autonomic responses.

CPAP is where a machine helps the OSA patient breathe more easily while asleep.

Funds from the National Institutes of Health and the National Institute of Nursing Research helped finance the study.

In another study published recently, researchers from Brigham and Women's Hospital in Boston, MA, found that sleep apnea is linked to early sign of heart failure.