My mom suffers from bouts with chronic insomnia, so I try to keep up with any news or treatment for the debilitating condition as a concerned son. It appears there's a development on the horizon which may help sleep sufferers improve the quality of sleep...and possibly enhance brain activity while awake...all via headphones.
Science Dailyreports German researchers subjected test participants to pink noise (an example above) tuned to their brain waves, right before entering deep sleep (if you need additional explanation about the difference between white vs. pink noise like I did, check out this slightly technical description). Those exposed to the tuned sounds exhibited longer periods of slow wave deep sleep. Not only were participants better off in the deep sleep department, but they were able to retain memory of words they were exposed to before entering sleep. So what does this mean for sleep sufferers? Possibly future developments where software/hardware can offer users audio programming fine-tuned to stimulate better sleep, and maybe even enhanced memory simply through the power of sound.
Unfortunately, if you're suffering from sleep issues now, there isn't yet an app or non-invasive device which can stimulate the deep sleep state cited above (though there are plenty of white noise devices options available).
But relaxation via sound is pretty well documented, including a recent study which rated and listed the most effective songs for inducing a relaxed state, before nearing a deep sleep slate. Readers also chimed in plenty with their favorite relaxing tunes, offering sleep sufferers an assortment of options for auditory exploration, hopefully to the realm of relaxed and deep sleep.