Older women with moderate to severe breathing problems during sleep are more likely to experience decline in ability to perform daily tasks, according to a recent study.

Researchers from Johns Hopkins Bloomberg School of Public Health and the University of California, San Francisco found that older women with disordered breathing during sleep were more than twice as likely to have difficulty performing daily activities, such as grocery shopping and meal preparation.

Sleep-disordered breathing involves repeated interruptions or decreases in breathing during sleep, which often leads to fragmented sleep and hypoxemia, or low blood oxygen levels. Doctors rate the severity of sleep-disordered breathing with the apnea-hypopnea index (AHI), which reflects the number of breathing interruptions (apneas) and the number of significant decreases in breathing (hypopneas) per hour of sleep.

For the study, researchers collected data from more than 300 women with a mean age of 82.3 years. At the start of the study, participants underwent an in-home sleep evaluation. They were also asked whether they had any difficulty performing daily activities, including heavy housework, shopping and preparing meals, or any challenges with mobility, such as walking several blocks or climbing or descending stairs. Participants' self-reported daily activities and mobility were assessed once again in a follow-up evaluation.

Researchers found that that women with an AHI on the moderate to severe side, with 15 or more breathing disruptions per hour of sleep, had 2.2 times greater odds of decline in daily activity functions during the evaluation period, which averaged five years between baseline evaluation and follow-up.

"Because sleep-disordered breathing can be treated effectively, it is possible that treatment could help prevent decline in important areas of functioning that allow older adults to remain independent," Adam Spira, the study's lead author, said in a statement. "As is often the case, more research is needed to investigate this possibility."

The findings are notable given the aging of the population -- an estimated 3.7 million Americans will turn 65 years old in 2015, and by 2030, 19 percent of the United States population will be 65 years or older -- and the fact that sleep-disordered breathing is treatable. Older adults are as much as four times as likely as middle-aged individuals to have problems with breathing during sleep.

The study is detailed in the Journal of the American Geriatrics Society.