If you've ever slept in a city apartment, near a highway, or next to a partner who snores, you already know the problem: your brain won't stop listening. Every car horn, door slam, and sudden creak pulls your nervous system out of sleep — sometimes fully, sometimes just enough to wreck the quality of whatever rest you're getting. Dr. Matthew Walker, neuroscientist and author of Why We Sleep, has a straightforward recommendation for this: use white noise to mask the disruptions. But what he also knows — and what most people miss — is that masking noise is only half the equation. The other half is getting your brain deep enough into sleep that those disruptions stop mattering at all.
That's where binaural beats come in. And when you layer both together correctly, you get something neither can do on its own.
What Matthew Walker says about white noise and sleep
Dr. Walker — founder-director of the Center for Human Sleep Science at UC Berkeley — has addressed white noise machines directly. His position is nuanced: the data on white noise is mixed in general, but in noisy environments, the benefits are real. In high-sound-pollution contexts like New York City, white noise machines have shown measurable improvements in sleep quality by masking the external sounds that would otherwise fragment your sleep cycles.
Walker also points to pink noise — a variant with more bass and less treble — as having distinct advantages. Pink noise has been shown to increase total sleep time and enhance the quality of both REM sleep and Stage 2 non-REM sleep, which are critical phases for memory consolidation and learning. The mechanism isn't complicated: pink noise is more natural-sounding than pure white noise (think rainfall or ocean waves rather than TV static) and tends to be less fatiguing to the auditory system over long periods.
But here's the critical insight that most people take away from Walker's work: white noise and pink noise work primarily as shields. They raise the baseline ambient sound level in your room so that sudden spikes — a dog barking, a truck braking, your neighbor's 1 AM door slam — don't punch through the silence and trigger your brain's threat-detection system. That's the concept of auditory masking, and the research supports it clearly.
The science of auditory masking
A 2021 study published in Sleep Medicine — co-authored by researchers at Weill Cornell Medical College — tested white noise on participants living in high-noise environments in New York City. The results confirmed what Walker describes: white noise significantly reduced the impact of environmental noise spikes by raising the acoustic floor. When there's already a consistent layer of broadband sound in the room, a sudden noise needs to be proportionally louder to register as a disturbance. Your brain's threshold for waking up goes up.
A 2025 Mayo Clinic systematic review of nearly 2,000 studies reached a similar conclusion: white noise and similar masking sounds consistently improved sleep efficiency in hospital patients — one of the noisiest environments a person can try to sleep in. In one coronary care unit trial, patient sleep quality scores more than doubled after three nights of white noise exposure.
The principle behind all of this is simple. Your brain doesn't fully shut off its auditory processing during sleep — it can't, because hearing evolved as a survival mechanism. Sounds are constantly being evaluated at a subconscious level, and anything that deviates sharply from the baseline ambient noise triggers an arousal response. White noise makes the baseline consistent. No sharp contrasts means fewer arousals.
The problem white noise doesn't solve
Here's what most articles about white noise leave out: masking noise doesn't make your sleep deeper. It just removes some of the things that make it shallower. There's a meaningful difference.
White noise can prevent you from being pulled out of sleep by external sounds, but it doesn't actively push your brain into the deeper stages of sleep — the slow-wave delta sleep where your body does its heaviest repair work, consolidates memories, clears metabolic waste from the brain, and resets your immune system. If you're someone who lies awake with a racing mind, or who falls asleep but never feels truly rested in the morning, masking noise alone isn't going to solve the underlying problem. Your brain is staying in lighter sleep stages, cycling through N1 and N2 without spending enough time in N3 deep sleep.
This is where the research on binaural beats becomes relevant — and where combining the two approaches creates something genuinely more effective than either one alone.
How binaural beats push sleep deeper
We covered the science of binaural beats in detail in our previous post on binaural beats and sleep, but here's the essential framework: when your ears receive two slightly different frequencies — one in each ear — your brainstem perceives a third tone at the difference between them, and your neural oscillations begin to synchronize toward that frequency. This is called brainwave entrainment.
For sleep specifically, the frequencies that matter are delta (1–4 Hz) and theta (4–8 Hz). Delta waves are the signature brainwave pattern of deep slow-wave sleep. Theta waves characterize the transition zone between wakefulness and sleep — that drowsy, pre-sleep state where your thoughts start to dissolve. By presenting binaural beats in these frequency ranges, you're giving your brain a target to synchronize toward, actively guiding it into deeper sleep stages rather than just hoping it gets there on its own.
A 2024 University of Tsukuba study published in Scientific Reports found that ultra-low frequency binaural beats at 0.25 Hz shortened the time it took participants to reach both N2 and N3 sleep stages. The researchers noted increased parasympathetic nervous system activity — your body's "rest and digest" mode — and reduced anxiety markers. Other studies have shown that delta-frequency binaural beats measurably reduce cortisol levels and heart rate variability patterns associated with stress.
In other words: white noise prevents disruptions from pulling you out. Binaural beats actively push you in.
The two-layer approach: why combining them works
Think of it as a defensive layer and an offensive layer working in concert.
The white noise layer handles your environment. It creates a consistent acoustic floor that raises the threshold for auditory arousals. Sudden noises — traffic, HVAC cycles, roommates, wind — get absorbed into the broadband sound rather than spiking above the silence. Your brain's threat-detection system stays quiet because there are no sharp contrasts to evaluate.
The binaural beats layer handles your brain. While the white noise keeps external disruptions from fragmenting your sleep, the low-frequency beats are working at a neurological level — encouraging your brainwaves to synchronize toward delta frequencies, deepening your sleep stages, and making those stages more resilient. When you're in deep N3 slow-wave sleep, your arousal threshold is already significantly higher than in lighter stages. You're naturally harder to wake. The masking noise has to do less work because your brain is in a state that inherently filters out more.
This is the key insight: the deeper you sleep, the less noise matters. Deep slow-wave sleep has the highest arousal threshold of any sleep stage. A sound that would easily wake you during N1 or N2 light sleep might not even register during N3. So binaural beats aren't just improving your sleep quality independently — they're amplifying the effectiveness of the white noise by putting your brain in a state where external sounds have progressively less power to disturb you.
Why the mix matters more than most apps realize
Most sleep apps treat white noise and binaural beats as separate features. Pick one or the other. Maybe they let you play rain sounds. Maybe they have a "binaural" category somewhere. But they almost never integrate the two in a way that respects the underlying neuroscience.
The problem with pure binaural beats in isolation is practical: they need to be audible to work, but they're tonal and repetitive, which some people find difficult to fall asleep to. And as Dr. Huberman has noted, binaural beats work best when they're not buried under heavy ambient sounds that mask the beat itself — you need the frequency difference to actually reach your brainstem.
The solution is careful layering with independent volume control. You want the white noise or nature sounds at a level that masks your environment, and the binaural beats at a softer level underneath — present enough for your brainstem to pick up the frequency differential, but not so loud they become distracting. This is a balance that a single volume slider can't achieve. You need control over each layer independently.
How IOn Sleep handles this
IOn Sleep was built with exactly this layering approach in mind. The app lets you mix up to three independent sound layers — each with its own volume control. You can set a white noise or rain layer at whatever level masks your environment, then add a delta or theta binaural beat layer underneath at a softer volume, and optionally add a third ambient texture (a low rumble, a distant storm, a river) to round out the soundscape.
For people who want the two-layer approach without manual mixing, IOn Flow automates the entire process. It starts with theta-range frequencies to ease your nervous system out of active thinking, then gradually transitions into delta frequencies as your brain descends into deeper sleep — all while you can layer environmental sounds on top at your preferred volume. It's the same progressive brainwave transition that the Frontiers in Neurology study protocol hypothesized should outperform any static single-frequency approach.
And because IOn Sleep runs entirely offline with a privacy-first approach, there's no background telemetry eating your battery or cataloging your sleep habits. Your phone becomes nothing but a sound engine — exactly what it should be at 2 AM.
Practical setup for tonight
If you want to try the two-layer approach, here's what the research suggests:
Choose your masking layer. White noise works, but pink noise or nature sounds (rain, ocean, fan) tend to be more comfortable for long-duration listening. Set the volume just high enough that you can't clearly distinguish individual sounds from your environment — that's your masking threshold.
Add binaural beats underneath. Start with theta (4–8 Hz) for the first 15–20 minutes as you wind down, then switch to delta (1–4 Hz) for the rest of the night. Or use a dynamic program like IOn Flow that handles the transition automatically. Keep the volume lower than your masking layer — the beats should be audible but not dominant.
Use headphones or earbuds. Binaural beats require separate frequencies in each ear. Speaker playback won't produce the entrainment effect. Comfortable sleep earbuds or a headband speaker are worth the investment if you're serious about this approach.
Set a timer. Both Walker and the broader sleep research suggest that continuous sound all night isn't necessary for everyone. The first 30–60 minutes — the sleep onset window — is when masking and entrainment matter most. Once you're in deep sleep, your arousal threshold is high enough that moderate environmental noise is unlikely to wake you. IOn Sleep's sleep timer lets you fade everything out gradually so the silence doesn't jolt you awake.
The bottom line
Dr. Matthew Walker is right: white noise masks the disruptions that fragment your sleep. The research is clear on that, especially in noisy environments. But masking is defense. It keeps bad things from happening. It doesn't actively make good things happen.
Binaural beats in the delta and theta range are the offensive counterpart — actively guiding your brainwaves into deeper sleep stages where external sounds lose their power to disturb you in the first place. Layer the two together and you get a system that simultaneously shields you from your environment and drives your brain toward the deep, restorative sleep your body actually needs.
That's not a marketing claim. That's what the peer-reviewed research points toward, and it's exactly the approach IOn Sleep was designed to deliver.