Hearing loss is a common and under-recognized public health problem that can influence a child’s educational, psychological and social development. However, little data was available to determine whether the prevalence of hearing loss in children has changed over time until recently when researchers at Brigham and Women’s Hospital (BWH) determined that hearing loss in adolescents has increased over the past 15 years. The findings are published in the August 18 issue of the Journal of the American Medical Association.

“We have known for a few years that hearing loss is very common in US adults,” said lead study author Josef Shargorodsky, MD, a physician-investigator at the Channing Laboratory at BWH. “However, an understanding of hearing loss in adolescents can help to paint a better picture of overall hearing loss in the US, and aid in further identifying potential causes of hearing loss.”

The researchers looked at data from the National Health and Nutrition Examination Surveys of adolescents from across the US, age 12 to 19 years old. Researchers found that currently, one out of five adolescents has some evidence of hearing loss, while one out of twenty has at least mild hearing loss. Compared to data from the survey from 1988-1994, there has been a marked 30 percent increase in prevalence of any hearing loss, and a 70 percent increase in mild or worse hearing loss in the past 15 years.

“What makes hearing loss in adolescents even more concerning is previous research showing that teens underestimate the importance of hearing and the dangers of noise exposure, and don’t make protecting their hearing a priority,” said Dr. Shargorodsky, citing a study that found that hearing loss ranked low as a health concern, even though most admitted to experiencing ringing in the ears or some hearing impairment after attending loud concerts and clubs. As hearing loss itself is invisible and often underestimated, researchers hope this study will help raise awareness in both teens and adults of the importance of  hearing conservation and encourage efforts to prevent hearing loss.

The researchers also found that hearing loss is more prevalent in adolescent males than females and more common in adolescents living below the US designated poverty level. “Further research is needed to better understand the causes of hearing loss, why it’s increasing in prevalence and why it affects some populations more than others,” said Dr. Shargorodsky.

The study was funded by the Massachusetts Eye and Ear Infirmary Foundation and Vanderbilt University School of Medicine Development Funds.

Ever wonder why some people can sleep through just about anything, while others get startled awake at each and every bump in the night? A new report in the August 10th issue of Current Biology, a Cell Press publication, offers some insight: sound sleepers show a distinct pattern of spontaneous brain rhythms.

"We found that by measuring brain waves during sleep, we could learn a lot about how well a person's brain can block the negative effects of sounds; the more sleep spindles your brain produces, the more likely you'll stay asleep, even when confronted with noise," said Jeffrey Ellenbogen of Harvard Medical School.

During sleep, brain waves become slow and organized, Ellenbogen explained. Sleep spindles refer to brief bursts of faster-frequency waves. Those bursts of activity are generated by a portion of the brain called the thalamus, which serves as a way station for most types of sensory information (everything except smell).

"The thalamus is likely preventing sensory information from getting to areas of the brain that perceive and react to sound," Ellenbogen said. "And our data provide evidence that the sleep spindle is a marker of this blockade. More spindles means more stable sleep, even when confronted with noise."

Ellenbogen said he and his colleagues were surprised at the magnitude of the sleep spindle effect. They observed brain patterns of study participants as they slept in the lab for three nights. The first night was quiet and the second and third nights were noisy, as the researchers introduced a variety of sounds—a telephone ringing, people talking, hospital-based mechanical sounds, and so on. "The effect of sleep spindles was so pronounced that we could see it even after just a single night," he said.

The researchers say they hope to devise ways to enhance sleep spindles via behavioral techniques, drugs, or devices, but it's not yet clear how to do that.

Ellenbogen said such advances would be particularly welcome today, as "our sleeping environments have gotten increasingly complex and problematic, with all the beeps and boops of our 24/7 modern, crowded lives. And there are particular challenges in a hospital setting where some of the sounds are necessary (e.g., heart monitors need to send an alarm if there's a problem). Our goal is to find brain-based solutions that integrate a sleeping person into their modern environment, such that sleep is maintained even in the face of noises. This finding gets us one important step closer to realizing that goal."

Ellenbogen ultimately envisions a future in which we'll have access to multiple strategies, based on sound sleep science and technologies, to help keep us asleep when we want to sleep and awaken us when it's time to get up. "In the meantime," he said, "it still doesn't hurt to put up a sign that says 'Shhh!'"

Another piece of advice for those who really must go to sleep with the radio or TV on: use a timer. The researchers' evidence shows that such noises do disrupt sleep, whether the sleeping person realizes it or not.