NEW YORK (Reuters Health) - Losing weight through lifestyle changes can improve or even reverse mild cases of the nighttime breathing disorder, sleep apnea, a new study suggests.

The study, of 72 overweight adults with mild obstructive sleep apnea (OSA), found that those placed on a diet-and-lifestyle regimen not only lost weight but showed significant improvements in their sleep apnea.

OSA occurs when the soft tissues at the back of the throat temporarily collapse during sleep, causing repeated breathing interruptions. Major symptoms include loud snoring and daytime sleepiness.

Over one year, participants lost about 22 pounds, on average, and the more weight they lost, they more likely they were to see their OSA go away.

Of those who managed to shed more than 33 pounds, 88 percent no longer had OSA by the study's end. That figure was 62 percent among patients who lost between 11 and 33 pounds, the researchers report in the American Journal of Respiratory and Critical Care Medicine.

The findings suggest that weight loss through lifestyle change is a "feasible and effective treatment for the majority of patients with mild OSA," write the researchers, led by Dr. Henri P.I. Tuomilehto of the University of Kuopio in Finland.

People with OSA have a heightened risk of heart disease. It's thought that repeated bouts of oxygen deprivation during sleep may, for example, raise blood pressure, which takes a toll on the cardiovascular system over time.

In this study, OSA patients' weight loss was accompanied by improvements in their heart risk factors, including high blood pressure and high cholesterol.

For their study, the researchers randomly assigned the 72 overweight, middle-aged adults in the early stages of OSA to either take part in an intensive lifestyle-change program or receive standard advice on diet and exercise.

The former group first went on a low-calorie diet for 12 weeks, restricting themselves to 600 to 800 calories per day. They also had several counseling sessions on how to keep up a healthier diet and start an exercise routine.

The positive results suggest that similarly intensive lifestyle changes should begin soon after OSA is diagnosed, Tuomilehto and his colleagues write.

"A more aggressive treatment of obesity in patients with OSA is well founded," they conclude.

SOURCE: American Journal of Respiratory and Critical Care Medicine, February 15, 2009.

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