Among the roughly 40 million adults in the U.S. who have hearing loss, most don't use hearing aids. This means they may be missing out on more than just good hearing.

Research shows hearing loss, if left untreated, can increase the risk of frailty, falls, social isolation, depression and cognitive decline. One study from scientists at Johns Hopkins University found that even people with mild hearing loss doubled their risk of dementia.

Now a new study finds that restoring hearing loss with hearing aids may lengthen people's lives.

Dr. Janet Choi, an otolaryngologist with Keck Medicine of USC, wanted to evaluate whether restoring hearing with hearing aids may increase the chances of living longer.

Using data from the the National Health and Nutrition Examination Survey, a large, national study, Choi and her colleagues tracked the status of nearly 1,900 adults who had been shown to have hearing loss during screenings. The participants completed questionnaires about their use of hearing aids.

"The group of patients who were using hearing aids regularly had a 24% lower risk of mortality compared to the group who never use hearing aids," Choi says. Meaning, the participants who were in the habit of wearing hearing aids were significantly less likely to die early.

The researchers had hypothesized this would be the case given all the studies pointing to the negative impacts of untreated hearing loss. But Choi says they did not expect such a big difference in mortality risk. "We were surprised," she says.

Prior research has shown that age-related hearing loss – if untreated – can take its toll on physical and mental health. And a recent study found restoring hearing with hearing aids may slow cognitive decline among people at high risk.

This new study, which was published in The Lancet Healthy Longevity Wednesday, adds to the evidence of benefit. The findings do not prove that it's the hearing aids that lead to longer life. It could be that people who regularly use hearing aids are also more likely to stave off isolation, remain more active or have reduced risk of falls, which could explain the increased longevity. The effect held up even when the researchers accounted for differences such as age, ethnicity, education and medical history.

Given the benefits, Choi says it's stunning how few people with hearing loss wear hearing aids regularly – just 12%, according to her study.

And Choi says another striking finding is that, the people in the study who had hearing aids, but didn't use them regularly, were as likely to die prematurely as those who never used them.

Choi recommends new users wear their hearing aids every day for 30 consecutive days to get used to them.

"Hearing loss is an invisible problem, and it happens gradually, so it takes time for you to get used to hearing aids and then get the benefit," she says.

Choi knows from personal experience the difference hearing aids can make. She was born with hearing loss in one ear. And for years she says she resisted the idea of wearing hearing aids, given that her hearing was very good in one ear. But when she became a surgeon she realized she was missing out.

"In the operating room during surgery, sometimes if someone talked to me on the left side when there was a lot of background noise, I usually wouldn't respond," she says. "People thought that I was just ignoring them, which was actually not true. I just didn't hear them."

Now she uses hearing aids regularly. "There were a lot of sounds I was missing," she says. Now, her hearing has greatly improved. "I'm very happy I got hearing aids," she says.

There can be several barriers to restoring hearing, including the cost of evaluation and the cost of hearing aids. But the technologies have improved and there are more affordable options compared to several years ago. Still, some people avoid wearing them due to stigma or the annoyance of getting used to them.

So, if you have hearing aids sitting in the back of a drawer, not being used, Choi says, try them again.

This story was edited by Jane Greenhalgh