Binaural beats for sleep

Binaural beats are a real trick of hearing, first described in 1839. Whether they change how you sleep is a much more open question. Here's how they work, what the studies say, and how to try them sensibly.

How binaural beats work

Play a 200 Hz tone in your left ear and a 204 Hz tone in your right. Neither ear hears anything but a steady note. Yet most people perceive a soft "wah-wah-wah" pulsing four times a second. That pulse doesn't exist in either sound. Your brain creates it while combining the signals from both ears, and the pulse rate equals the difference between the two tones.

That's a binaural beat. The Prussian physicist Heinrich Wilhelm Dove described it in 1839, and a 1973 Scientific American article by Gerald Oster brought it back into fashion. It works best with fairly low tones and small differences between the ears: a 2023 review puts the range where people perceive the beat at about 1 to 30 Hz.

Because the effect needs each ear to get its own tone, headphones are required. Through a speaker, the two tones mix in the room and you hear an ordinary "monaural" beat instead.

Why sleep apps use them

Brain activity during sleep and drowsiness includes slow rhythms that researchers group into bands: delta (roughly 0.5 to 4 Hz) and theta (roughly 4 to 8 Hz). The idea behind sleep beats is called entrainment: if you listen to a beat at a delta or theta rate, perhaps your brain's rhythms drift toward it.

It's an appealing idea, and you'll see confident claims about it online. The evidence is a lot less tidy.

What the research actually says

On entrainment. A 2023 systematic review in PLoS ONE pulled together 14 studies that measured brain activity during binaural beats. Five supported entrainment, eight contradicted it and one had mixed results. The studies used very different tones, durations and measurements, which makes them hard to compare.

On how people feel. A 2019 meta-analysis of 22 studies found a moderate overall effect of binaural beats on memory, attention, anxiety and pain perception. That's encouraging, but those are daytime measures, not sleep, and the authors themselves note the effect depends heavily on the frequency, timing and length of listening.

On sleep itself. Studies are few and small. In one 2018 lab study, 24 young adults slept in a lab for three nights. On the last night, 16 of them heard a 3 Hz beat from the start of stage N2 light sleep until stage N3 began, while the other 8 got a silent sham. The beat group spent longer in N3, the slow-wave stage, than the control group. One small study isn't proof, and it used carefully timed stimulation that a phone app playing all night doesn't copy.

So the fair summary is: binaural beats are a real perceptual effect, some studies show interesting results, and nobody can honestly promise they'll change your sleep. If someone tells you otherwise, ask for the study.

Who might enjoy them

• People who already sleep in headphones, for example because of a snoring partner.
• People who like a minimal, humming background more than nature sounds or music.
• The curious. If you're interested in how hearing works, it's a fun effect to experience. Try a few nights and judge by how you feel, not by a promise.

If you don't like sleeping in headphones, a plain sound like pink noise or gentle sleep music through a speaker will probably suit you better.

How to try them at night

1. Use comfortable headphones. Hard earbuds get sore when you lie on your side. Soft sleep headphones or a headband are easier.

2. Keep the level very low. You'll be listening for hours with sound close to your eardrums. See our guide to how loud sleep sounds should be, including iPhone's built-in headphone level meter.

3. Layer, don't isolate. A pure beat on its own can sound clinical. Many people prefer it blended quietly under rain or music.

4. Use a timer. Since the theory is mostly about the transition into sleep, there's little reason to keep a beat running all night. A 30 to 60 minute timer with a fade is a sensible default.

5. Give it a fair trial and be honest with yourself. Three or four nights, then ask whether you actually like it.

In the SleepBetter.ai app

The app's brainwave beats are generated live on your iPhone rather than looped from a recording, so every frequency is exact. There's a range of presets, including ones for falling asleep and for a short nap, and you can layer a beat softly under any sound and set the balance with a blend slider. The app says it plainly: beats work best with headphones. The sleep timer fades everything out gently.

A note on claims

You'll find apps and videos promising that a particular frequency will make you fall asleep in minutes, boost hormones or "reset" your brain. We don't make those claims, because the research doesn't support them. Enjoy beats as a pleasant sound you can test for yourself.

This page is general information about sound and sleep habits, not medical advice. If poor sleep is affecting your days, talk to a doctor or a sleep specialist.