The claims for this sleepy-time sound effect are all over the place—so is the science.
If you've ever gone looking online for soundtracks to aid sleep or relaxation, you've likely run across binaural beats. Available in specialized apps and plentiful on streaming sites, these whirring, vibrational sounds come in different varieties, each associated with a tantalizing benefit. Purveyors of binaural beats promise everything from deeper sleep to memory improvements and enhanced focus, depending on the track.
You might suspect the many claims attached to binaural beats are overblown. Spoiler alert: You're probably right. But surely these tracks, some of which garner tens of millions of views on YouTube, must have something to them.
Could they be worth a listen for better sleep?
What Are Binaural Beats?
A binaural beat is two tones played at slightly different frequencies in each ear, creating an auditory illusion. For example, if you listen to a tone at 440 hertz on one side and 446 hertz on the other, your brain will "hear" a 6-hertz tone—the difference between the two frequencies. Played on their own, binaural beats tend to sound like an echoing hum, but some tracks layer on music or other sounds so that the beat is practically inaudible.
The different frequencies of binaural beats are meant to correspond with five established categories of brain waves, or measurements of electrical activity among neurons, which are denoted by Greek letters. These, in turn, map to different mental states and activities. Theta waves, for instance, fall within around the 4- to 8-hertz range and are associated with deep relaxation; the buzzier gamma brain wave, at 30 hertz and higher, relates to stimulation and attention.
The idea behind binaural beats is that you can back yourself into a state of mind, in a sense, by playing the frequency associated with the mood you want. Your brain waves synchronize with the tone, and—at least in theory—your mental state then synchronizes with your brain waves.
Do Binaural Beats Work?
In a study published earlier this year, researchers played two types of binaural beats for 16 participants and compared the effects with those for monaural beats, in which two tones are combined on one track that is played in both ears. The participants' brain wave frequency did indeed synchronize with that of the binaural beats—a phenomenon called entrainment—but they did so even more with monaural beats, and neither produced a change in self-reported mood.
The fact that brain waves would match up with the binaural beats isn't remarkable, says Hector Orozco Perez, who conducted the research as a graduate student at McMaster University in Ontario, Canada.
"If you are listening to a rhythmic stimulus, your brain will entrain to it," he says. "That's the way the brain works."
But the fact that your brain waves mirror an external sound doesn't necessarily translate to a change in your mood—and in fact, it didn't for any of the participants in the study. Orozco Perez says he knows people who feel benefits from using binaural beats. He doesn't deny that it’s possible, he simply questions the mechanism: "It might be a placebo [effect]. It might also be the fact that it's a rhythmic stimulus."
Leila Chaieb, Ph.D., a researcher at the University of Bonn in Germany, has found that binaural beats (along with monaural beats) might be helpful in encouraging focus among people whose minds tend to wander. And in a separate review of existing literature on the subject, she and colleagues noted evidence that the beats can decrease anxiety.
Proven study-based benefits of binaural beats improving sleep, however, are scarce. That said, however, both Chaieb and Orozco Perez agree it can't hurt to try them.
“Apply this sound stimulation for short durations and at lower frequencies to avoid headache, fatigue, and tinnitus," Chaieb recommends, pointing out that none of the participants in any of her studies reported any negative side effects from listening to binaural beats.
The bottom line: While the current science may not definitively prove that binaural beats promote sleep or relaxation, that doesn't mean they won't help you. There are many open questions surrounding this kind of auditory stimulation and many different parameters to test, says Orozco Perez. Also, as Chaieb points out, there is demonstrated potential for binaural beats to boost focus and lower anxiety.
Once thoroughly tested, she adds, binaural beats could be accepted as a useful tool in helping people alleviate anxiety symptoms non-invasively and safely, which, in theory could help you sleep easier.
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