Consider the stress of modern life, with its cacophonous soundtrack of traffic, electronics and construction. It's no wonder so much of our leisure time is spent in a quest to let go of the workday and unwind. But sometimes our lifestyles conspire against us, and it's almost impossible to unplug, relax and fall asleep.

Studies have estimated that one-third of all adults in the U.S. cope with insomnia. The resulting fatigue-related injuries and loss of work productivity take a heavy toll on people's lives and costs employers billions of dollars annually.

Despite these serious consequences, according to Penn State Professor of Psychology Rich Carlson, insomnia goes largely undertreated by health care providers, with many people seeking relief through alcohol, over-the-counter medicines, and -- increasingly -- advice found online.

One of the most popular recent self-help trends for insomnia and anxiety is also among the more unusual ones. Autonomous Sensory Meridian Response, or ASMR, is a term coined in 2010 to describe "sounds that feel good." The sound of whispering is considered the most common trigger for the ASMR feelings. Other triggers can be things such as the scratching sound of a pen on paper, rhythmic monotone speech or tapping fingernails.

Not all triggers are sounds. Having someone focus intently on you -- such as during a haircut or an eye exam -- can bring on the pleasurable fizzle of ASMR, some people say. People experience ASMR episodes in different ways, but usually report feeling a relaxing tingling sensation in the back of the head, between the shoulder blades or down the spine.

There may be two things taking place, says Carlson. "One is the feeling of relaxation or stress relief, which is probably similar to what people experience listening to soothing music or natural sounds like running water or waves at the seashore. That might work by providing something to pay attention to other than stressful thoughts, or perhaps by providing an external stimulus to which breathing might be synchronized. They might also work by giving people a focus for achieving a meditative state. Research has provided evidence that this can help with anxiety."

The other explanation for ASMR's popularity, notes Carlson, may be "the physical sensation that some people report, such as a tingling scalp. It would be interesting to understand the mechanism of this phenomenon, but I haven't seen anything that resembles it in the scientific literature."

While the scientific evidence may be lacking, proof of ASMR's popularity is easy to find. YouTube boasts over a million ASMR videos created by hundreds of devotees for the purpose of helping people relax and sleep. Oddly enough, episodes of "The Joy of Painting" television show -- known for the soothing voice of its late host, painter Bob Ross, and the sound of brush strokes on canvas -- are an ASMR favorite on YouTube as well.

Some say there's a connection between ASMR and binaural beats, an auditory relaxation technique based on the way the brain interrupts sounds of different frequencies. Very preliminary research suggests there may be some reported anti-anxiety effect for people listening to binaural beat recordings.

"I don't see an obvious connection between ASMR and the binaural beat phenomenon," says Carlson, "but we do know that external events like sounds can result in entrainment of physical events like breathing. That is, breathing can become synchronized with sound, and we know that slowing one's breathing can have a calming effect. There's also evidence that neurofeedback (information about your own brainwaves) can help people control their anxiety, so perhaps ASMR or binaural beats have a similar effect."

Whether there turns out to be some validity to ASMR or not, its popularity might signal something about the country's frustration with existing methods for treating insomnia and anxiety. Yet, as Carlson notes, "often the public's enthusiasm for a phenomenon far exceeds the eventual scientific evidence for it. One could point to the 19th-century fascination with séances or phrenology (assessing personality by measuring the skull) or the more recent excitement about subliminal advertising or subliminal messages in music recordings. The popularity of ASMR may well be a response to the desire for methods to reduce stress and anxiety, or in part fascination with a surprising, counterintuitive kind of experience reported by others."

If there's a danger in this, it's probably that some people with severe anxiety or sleep disorders might put off seeking help because they believe a self-help approach will work, cautions Carlson. "People should always seek professional medical guidance for their physical or mental health concerns, including insomnia and anxiety," he explains. "I don't see much risk of personal harm. I frequently listen to music to help me relax, and if listening to something else works for others, that seems fine to me."

At the moment, the phenomenon is purely anecdotal, he says, and some people don't feel anything in response to so-called ASMR triggers. "To my surprise," Carlson says, "I experienced the tingling myself when listening to the whispering videos, although to me the sensation was not especially pleasant. It was more like the reaction I have when something tickles the hair on the back of my head."

People should understand, he adds, that "our individual expectations play a major role in the psychological effects we experience around many things, likely including the ASMR videos." And they should be aware too, he notes, that YouTube is an unlikely source for a miracle cure for serious problems. "There are at least dozens, probably hundreds, of self-help websites for managing anxiety, and they often include a mix of common-sense approaches, ideas modeled on cognitive-behavioral and other psychological techniques, as well as approaches that seem likely to be based on superstition or wishful thinking."

Richard Carlson is professor and associate head, Department of Psychology, College of the Liberal Arts, Penn State. He can be reached at racarlson@psu.edu.