Binaural beats did not calm dental anxiety in a trial

Search for anything about sleep or stress and the algorithm will eventually offer you binaural beats: two tones, one per ear, promising to tune your brain into calm. It is a large category of content with very little in the way of trials in settings where anxiety actually matters.

A dental surgery unit is such a setting. Ninety patients were assigned equally to binaural beats, isochronic tones, and control groups, all of them having an impacted lower wisdom tooth removed.

No between-group differences were observed in the anxiety questionnaire scores.

What binaural beats are supposed to do

The trial tested two forms of auditory stimulation. Binaural beats play a slightly different frequency into each ear, and the brain perceives a pulsing third tone at the difference between them. Isochronic tones are simpler: one tone, switched on and off at a fixed rate.

Both rest on the same premise, that a rhythm delivered through the ears will pull brain rhythms along with it and, through that, settle the body.

The body does have a settle-down state worth aiming at. Relaxation techniques are practices to help bring about the body’s relaxation response, which is characterized by slower breathing, lower blood pressure, and a reduced heart rate. The relaxation response is the opposite of the stress response.

Established ways of reaching it are unglamorous and involve doing something rather than hearing something. For breathing exercises, you might focus on taking slow, deep breaths, also called diaphragmatic breathing. In guided imagery, you picture objects, scenes, or events that are associated with relaxation or calmness.

Audio asks less of the listener, which is most of its appeal.

Why dental surgery is a good test

Anxiety is a feeling of fear, dread, and uneasiness. It might cause you to sweat, feel restless and tense, and have a rapid heartbeat, and it can be a normal reaction to stress.

Dental fear sits at the sharper end of that. People with phobias have an intense fear of something that poses little or no actual danger, and dental anxiety is common enough that the researchers open on it: dental anxiety is a common problem in oral surgery practices.

The setting is useful precisely because the stress is real, scheduled and identical for everyone. Nobody has to be reminded of a stressful memory in a laboratory. They are about to have a tooth cut out of their jaw.

That also makes it a fair test. If a calming intervention cannot be detected here, the question of where it can be is a reasonable one.

How the binaural beats trial was run

Ninety patients were assigned equally to binaural beats, isochronic tones, and control groups, with the control group receiving no intraoperative auditory stimulation.

Everyone had the same operation: the removal of an impacted lower wisdom tooth.

The measurements came in two kinds. Anxiety levels were assessed using four instruments, pre- and postoperatively, three of them standard questionnaires and one a simple line on which patients mark how anxious they feel.

Alongside that, physiological parameters including respiratory rate, pulse rate, blood pressure and oxygen saturation were recorded at eight surgical stages.

What the anxiety scores showed

Nothing, is the short answer.

No significant between-group differences were observed in the pre- or postoperative anxiety questionnaire scores. Four different ways of asking how anxious someone felt, and the group listening to binaural beats did not separate from the group listening to silence.

The authors state the conclusion plainly. The findings indicate that binaural beats and isochronic tones have a limited effect on reducing dental anxiety during impacted mandibular third molar surgery and do not support a definitive anxiolytic benefit.

The two results that did move, and why to be careful

The paper reports isolated between-group differences in physiological parameters: systolic blood pressure at the moment of incision was lowest in the binaural beats group, and breathing rate during anesthesia was lowest in the isochronic tones group.

Those are the kind of findings that get pulled into a headline, so it is worth doing the arithmetic the abstract invites. Five physiological measures, recorded at eight stages of surgery, is on the order of forty separate comparisons.

Run forty comparisons on data where nothing is happening and a couple will come out looking notable anyway. That is not a criticism of the researchers, who describe these as isolated and do not build their conclusion on them. It is the reason a single unexpected number in a large grid of numbers should not be read as a finding.

The pattern also argues against itself. One measure favored one intervention at one moment; a different measure favored the other intervention at a different moment. A real calming effect would be expected to show up more consistently than that.

Liking it is not the same as it working

The most interesting number in the paper is about preference. The majority of the binaural beats and isochronic tones patients, 78.3%, reported that they would prefer auditory stimulation in future dental treatments.

So most people wanted it again, in a trial where it did not measurably reduce their anxiety.

Both things can be true. Headphones during oral surgery mask the sound of the drill, mark the procedure as something being managed, and give a person something to attend to other than the hands in their mouth. None of that has to register on an anxiety questionnaire to be worth having.

It does mean that satisfaction surveys are a poor guide to whether an intervention does what it claims.

What this trial cannot settle

Thirty patients per group is small. An effect could exist and be too modest for this trial to see, and the authors do not claim otherwise.

One procedure, one clinic, one population, and a stress that lasts under an hour. Nothing here speaks to listening to binaural beats nightly for sleep, which is how most people actually use them.

The audio protocol matters too and is not standardized across this field. Different carrier frequencies, beat frequencies and durations are used in different studies, which is one reason results scatter. The authors say further studies using objective neurophysiological measures and standardized protocols are required, for exactly that reason.

The paper is paywalled, so the authors’ own limitations section was not available for this piece.

What to do with your calming playlist

Keep it, if it helps you. The honest summary is that a properly randomized test in a genuinely stressful setting did not find the effect the marketing promises, and that this is one small trial rather than a verdict.

What would be a mistake is treating audio as a substitute for the things that do have evidence behind them, or as a reason not to tell a dentist you are frightened. Dental anxiety is manageable, and the management usually starts with saying it out loud.

The broader lesson is portable. When a wellness product is tested properly and the headline outcome comes back flat, the interesting question is not whether a couple of secondary numbers moved. It is why the main one did not.

Non-drug approaches that ask something of the listener have fared better in trials. Slow pranayama, tested as an addition to psychiatric care, moved both anxiety scores and cortisol.