Neurostimulation & neurofeedback
Audiovisual / Brainwave Entrainment
Graded on: self-reported anxiety, sleep and pain; cognitive test scores.
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
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How this letter has changedLatest: August 2026 · Added.
Added as a device modality separate from 40Hz Gamma Sensory Stimulation, which sits in the same category and shares none of its literature. Three meta-analyses A study that pools the numbers from several trials into one combined estimate. of randomized trials carry the letter, all of binaural beats delivered through headphones: pooled g = 0.45 across cognition, anxiety and pain (Garcia-Argibay 2019, PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 30073406), g = 0.40 on memory and attention (Basu 2023, PMID 35842538), and SMD -1.38 on perioperative anxiety at 91.6 percent heterogeneity How much the results of the pooled trials differ from each other. High heterogeneity makes a combined estimate less reliable. (Xiong 2025, PMID 41176178). Every pooled endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. is self-report or a cognitive test score, so B is the ceiling before anything else is weighed. Graded C rather than B for three reasons: a systematic review A review that searches for every study on a question using a method set in advance, then assesses them together. of EEG recordings during stimulation found five studies supporting entrainment and eight contradicting it (Ingendoh 2023, PMID 37205669), so the named mechanism is not established; the comparator in these trials is blank audio or music and cannot be blinded; and no trial has reported a longevity endpoint. The graded form is tones alone. No light-and-sound headset has been tested as a unit in any pooled trial, which is why the one consumer product listed under this modality carries a low delivery fidelity.PMID 30073406 PMID 35842538 PMID 41176178 PMID 37205669
Every change to a letter on this site is dated and published. The full evidence log →
Audiovisual entrainment uses pulsing sounds or lights, such as binaural beats, to guide brain waves. Three reviews of studies found some effects on outcomes that people rate themselves. The studies varied a lot, and it is hard to hide from people which treatment they are getting. How it might work has not been shown.
Neurostimulation & neurofeedback · Brain entrainment
A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Rhythmic sound, and in consumer devices rhythmic light, delivered at a chosen frequency on the theory that electrical activity in the brain will fall into step with it. The pooled human trial evidence is real and it is narrow: three meta-analyses of randomized trials, all of binaural beats through headphones, all reporting on self-rated anxiety, sleep and pain or on cognitive test scores. Grade C reflects a ceiling of B for that class of endpoint, plus three things that keep it below the ceiling: an entrainment mechanism that repeated EEG studies have failed to confirm, comparators that cannot be blinded, and no longevity endpoint tested anywhere.
| What is graded | Auditory beat stimulation at a stated frequency, delivered through headphones, in sessions of roughly 10 to 30 minutes. That is the intervention the pooled trials tested. Light is not part of it. |
| Endpoints | Self-rated anxiety, self-rated sleep quality, self-rated pain, and cognitive test scores. Under EBL's grading rule, self-report and surrogate endpoints A lab value or measurement used in place of the outcome that matters, such as LDL cholesterol standing in for heart attacks. Moving a surrogate does not always move the outcome. cap at Grade B no matter how large the trial. |
| Key caveat | The mechanism is not established. A systematic review of studies that actually recorded EEG during stimulation found more studies contradicting entrainment than supporting it. A modality can produce an effect without its named mechanism being real, but the marketing rests on the mechanism. |
| Consumer devices | No light-and-sound headset has been tested as a unit in any pooled trial. A device that adds a visor, narration and music to the tones is delivering more than the graded intervention, and nothing isolates which part, if any, is responsible. |
| Not the same as 40Hz | 40Hz Gamma Sensory Stimulation is a separate modality with a separate literature: a fixed frequency, an Alzheimer's and mild cognitive impairment population, and imaging endpoints. The two are not interchangeable and evidence does not transfer between them. |
The pooled trials measured a single validated self-report instrument at fixed intervals: GAD-7 or STAI for anxiety, PSQI for sleep, at baseline and again after four and eight weeks. Session length in those trials ran roughly 10 to 30 minutes, and longer exposure predicted larger effects. The graded protocol is audio alone at a stated beat frequency, so sessions that add light or narration sit outside what was tested.
Pooled 22 studies of binaural-beat exposure on memory, attention, anxiety and pain perception. Overall effect g = 0.45, described by the authors as medium and consistent. Longer exposure and exposure beginning before the task predicted larger effects. Every endpoint is a self-report scale or a cognitive test score, and the stimulus in every pooled study is auditory.
Pooled 15 studies restricted to memory and attention. Overall effect g = 0.40. The authors' own systematic review alongside the pooled figure reports conflicting results within the theta and beta bands, so the pooled number sits on top of an inconsistent underlying literature rather than a settled one.
Perioperative use. Against blank audio, binaural beats reduced anxiety (SMD -1.38, 95% CI -1.89 to -0.87) and postoperative pain (SMD -0.61, 95% CI -1.03 to -0.19). Heterogeneity for the anxiety result was 91.6 percent, which is very high, and the endpoint is a self-reported anxiety scale in patients who know whether they are wearing headphones. The largest effect in this modality is also its least blindable.
Systematic review of 14 studies that recorded EEG activity during binaural-beat stimulation. Five supported the brainwave entrainment hypothesis, eight contradicted it, one was mixed. It carries no letter because it reports no clinical outcome. It is shown because it is the reason this modality is graded C rather than B: the mechanism the category is named after has not been demonstrated.
Eighty-four women with fibromyalgia randomized to brainwave entrainment delivered by a BrainTap headset or to music therapy, 20 minutes daily, five days a week for eight weeks, with six-month follow-up. Pain and anxiety fell in the entrainment arm. It is the only trial anywhere that tested a light-and-sound headset as a unit, and it cannot carry the grade: PubMed indexes it as Journal Article only, with no interventional publication type, and Rule 09 requires independently indexed interventional evidence. An unindexed design is a fact about the indexing, not about the study, which is why it is recorded in full rather than dropped. Its comparator was music therapy, not a sham A fake version of a procedure or device used as the comparison, so participants cannot tell which one they received..
Devices in this category that add flashing or pulsing light are a photic stimulus. Photic stimulation at frequencies in this range is the standard provocation used to elicit seizures during clinical EEG testing. Anyone with photosensitive epilepsy, a seizure history, or an unexplained loss of consciousness should not use a light-emitting device in this category without discussing it with their physician first. Audio-only sessions do not carry that specific risk.
Sessions are designed to induce drowsiness and reduced alertness. It is not for use while driving or operating machinery. Trials in this modality were short, ran in adults, and reported no serious adverse events, but none was designed or powered to detect them.
No medication interaction has been studied for this modality. Medications that lower the seizure threshold, including some antidepressants, antipsychotics and stimulants, are relevant to the photic point above rather than to the stimulation itself, and are a question for the prescribing clinician.
The gap on this page is between what is sold and what was tested. What was tested is tones through headphones, measured against how people said they felt afterwards. What is sold is a headset combining light, tones, narration and music, described in the language of neuroplasticity. Grade C is not a verdict that nothing happens. It is a statement that the trials measured self-report, that the mechanism named on the box has not been shown to occur, and that no trial has followed anyone long enough to say anything about aging at all.
Educational use only · Not medical advice · Starting, stopping or changing any supplement or medication is a decision for your physician
EBL does not verify the regulatory status of any device. Many consumer wellness devices are not FDA-cleared The FDA found a device substantially equivalent to one already on the market. Clearance is not approval and does not require trials showing benefit., and FDA clearance, where it exists, applies only to specific indications. The grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Using any device for a health purpose is a decision for your physician.
Primary evidenceThree papers, each linked to its PubMed record.
Garcia-Argibay et al. (Psychological Research, 2019; PMID 30073406), Basu et al. (Psychological Research, 2023; PMID 35842538) and Xiong et al. (Complementary Therapies in Medicine, 2025; PMID 41176178): three meta-analyses of randomized trials of binaural-beat stimulation. Grade C reflects self-reported endpoints, comparators that cannot be blinded, high heterogeneity, and a mechanism that has not been demonstrated.
Products carry no letter. The letter belongs to the therapy as the trials studied it, and no trial tested these products unless the entry says so. Listed alphabetically; payment does not affect order.
Light-and-sound headset paired with a session library. The Audiovisual / Brainwave Entrainment modality is graded C on self-reported anxiety, sleep and pain in trials of binaural beats delivered through headphones. This product adds four components those trials did not include, so the modality grade describes a narrower intervention than the one this device delivers.
Bundles five components at once: photic stimulation through the visor, binaural and isochronic tones, guided visualization narration, layered music, and auricular light in the earpieces. The graded trials tested tones alone. Nothing here isolates which part, if any, is doing the work.
This page carries a letter. EBL takes no commission, referral fee or payment of any kind on anything it grades. No letter has been bought and none is for sale. Products listed under this modality may be commercial partners, and their purchase links may earn EBL a commission. Those products carry no letter of their own, every relationship is disclosed beside the link, and where a product does not deliver what the trials tested, this page says so regardless of who pays.
How this is enforced
That is not a promise, it is a build condition. Two checks run on every deploy: one refuses to publish if a commission is claimed on anything graded, the other refuses if a page names a commercial relationship that is not declared in the register. If either fails, this page does not go live. You can read how the checks work, and what they do not cover, on the evidence integrity page.
These statements have not been evaluated by the Food and Drug Administration. Any grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Starting, stopping or changing any supplement or medication is a decision for your physician.
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