People with breathing problems that disrupt their sleep were less tired after three weeks of treatment with a breathing device compared to those treated with a placebo, U.S. researchers said on Saturday.

The findings show that regular use of treatment with continuous positive airway pressure (CPAP) masks reduces fatigue caused by obstructive sleep apnea, a chronic disorder that affects 12 million Americans.

Sleep apnea raises the risk of high blood pressure, heart attack, stroke, irregular heartbeat and diabetes.

It occurs when soft tissue in the back of the throat collapses during sleep, blocking the airway and causing the brain to rouse the sleeper, who gasps for air - a cycle that can occur as many as 30 times in an hour.

CPAP disrupts this cycle by providing a steady stream of air through a mask that keeps the airway open during sleep.

Companies that make CPAP treatments include Graymark Healthcare and ResMed Inc.

“These results are important as they highlight that patients who comply with CPAP therapy can find relief from fatigue and experience increases in energy and vigor after a relatively short treatment period,” Lianne Tomfohr of San Diego State University and the University of California, San Diego, whose study appears in the journal Sleep, said in a statement.

Several studies have shown that CPAP treatment can reduce other health risks, such as lowering the risk of stroke, but few have studied the impact on fatigue, which can reduce work performance and increase the risk of accidents.

For the study, Tomfohr and a team at the University of California, San Diego, studied 59 adults in their late 40s who had at least 10 partial or complete pauses in breathing per hour of sleep.

These volunteers were randomly assigned to get either CPAP or a sham therapy. Both groups were trained on the proper use of the equipment and filled out questionnaires.

After three weeks, volunteers who got CPAP treatment had significantly less fatigue on two independent scales measuring fatigue and they reported having more energy.

There was no such improvement among those who got the placebo treatment.

CPAP treatment is the most common treatment for sleep apnea.

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By Julie Steenhuysen

CHICAGO