Sensory Sensitivities at Bedtime

When every sound you try gets rejected, the sound is usually wrong — not the child

You bought the white noise machine everyone recommends. Your child hated it. You tried rain, then the sea, then a fan. Hated, hated, hated. At some point it starts to look like your child simply does not want to be helped.

Before accepting that, it is worth considering a much more boring explanation: to a sensitive ear, most of those sounds share the same property, and it is the property your child is objecting to.

It is also worth knowing how common this is. In a study of children with ADHD, hyperacusis — finding ordinary sounds uncomfortably or painfully loud — was identified in 36.7%, against 13.3% of children without ADHD. A separate assessment of children with developmental concerns found sound sensitivity was the most common sensory difficulty of all, and more than twice as common as touch sensitivity. So the child who needs sound to settle and the child who cannot bear it are not two different populations. They are frequently the same child, on different settings.

The Hiss Is Usually the Problem

White noise contains every audible frequency at equal intensity. Because human hearing is more sensitive to higher frequencies, that reads to the ear as bright and hissy — the untuned radio, the fan, the tap running.

For most people that is neutral background. For a child with sound sensitivity it can be genuinely unpleasant: a sharp, unrelenting layer sitting exactly in the range the ear notices most. Being told it is soothing does not make it feel soothing.

The useful part is that this is fixable without giving up on sound. Noise comes in different spectral shapes, and the difference between them is not subtle:

If your child has refused "white noise" once, they have not refused sound. They have refused one spectral shape of it, and it happens to be the harshest.

All three are in the app, stacked directly on top of each other in the sound mixer — white, then pink, then brown — each with its own volume slider. That ordering is deliberate: swapping between them takes seconds, so you can find out in one evening which spectral shape your child actually objects to rather than concluding that sound as a whole is the problem.

Sudden Is Worse Than Loud

The second thing sensitive children tend to object to is not volume but change. A steady sound at moderate level is far easier to tolerate than a quiet one that keeps doing something unexpected.

This is why several popular bedtime options fail for exactly the wrong reason:

• Nature recordings with events in them — a bird, a wave breaking louder than the last, a thunderclap. Each one is a small startle.
• Real orchestral recordings — genuine concert-hall performances are built on dynamic contrast. A crescendo arrives precisely when your child was finally drifting off.
• Playlists that change track abruptly — a hard cut between pieces is a change even when both pieces are calm.
• A timer that stops dead — sudden silence is itself a change, and often the thing that wakes a light sleeper.

This is the reason the app's catalogue is composed for sleep rather than borrowed from performance recordings: steady tempo, soft dynamics, no surprises. It is also why the sleep timer fades out gradually instead of switching off.

Let Your Child Be the Judge

With sensory sensitivity, guessing is inefficient and the child is a far better instrument than you are. The most productive twenty minutes you can spend is sitting down together in daylight, not at bedtime, and going through the sounds one at a time.

• Play each one on its own, briefly. Ask only two questions: is this fine, or is it annoying? Not "do you like it" — liking is a different and less useful question.
• Expect strong opinions and take them literally. A child who says a sound is horrible is reporting something real, even when the sound seems innocuous to you.
• Try the same sound at two volumes before ruling it out. Some sounds are unpleasant loud and unremarkable quiet.
• When something is accepted, save the mix as one of the three custom presets. It becomes theirs, restored with one tap.

Doing this away from bedtime matters. At bedtime everything is a negotiation and everyone is tired; in the afternoon it is just an interesting thing to try. It also gives a child who is directed all day a piece of genuine authorship over their own evening — which tends to reduce the arguing about it later.

There Is an Optimum, Not a Maximum

There is research suggesting that sound does not affect every brain the same way. In one study, the identical white-noise condition improved memory performance in children with attention difficulties and worsened it in children without them (Söderlund et al., 2007). The proposed explanation involves brain arousal levels: a brain sitting below its optimum is nudged toward it by outside input, while a brain already at its optimum is pushed straight past.

The practical consequence is the same in both directions — the response follows an inverted U. Too little does nothing, too much becomes another thing to react to, and the right amount is specific to the individual child. That is not a claim that any of this treats anything; it is the reason every sound in the mixer has its own slider rather than a single on/off switch. The fuller explanation is on the Science page.

Adjust in small steps across several evenings rather than all in one night. Otherwise you will not know which change did anything.

The Rest of the Room

Sound is the part this app can help with, but it is rarely the only sensory thing happening at bedtime. If sound alone does not resolve it, these are usually worth checking:

• Fabric and seams. Pyjama labels, waistbands, a duvet cover that feels different from last week. Small, and completely capable of ending an evening.
• Light. Standby LEDs, a gap in the curtains, a bright screen just before bed. A warm, dim night light is a different thing from a lit room — the app's is deliberately amber and very low, and can fade to a fully black screen while the music continues.
• Movement on the screen. For some children even a slowly drifting shape or a gently pulsing light is one thing too many. The night light has a no-motion switch that stops both at once — the shapes disappear, the pulsing stops, and what is left is a single still colour.
• Temperature. Slightly too warm is a common and easily missed cause of a child who cannot settle.
• Deep pressure. Many sensory-sensitive children settle better with a heavier duvet or being tucked in firmly. Weighted blankets suit some children but have real safety considerations by age and weight — worth asking your child's doctor rather than guessing.

A Note on Autism and Sensory Processing

Sound sensitivity is common in autistic children and in children with sensory processing differences, not only in ADHD. Much of this page applies equally, with one addition that matters more in that context: predictability. The same sequence, the same sounds, the same volume, every night — and the option to turn the visuals off entirely, which the app supports both with a fully black screen and with the no-motion night light. Repeating the identical evening is made deliberately easy: Same as last time restarts last night's exact setup — track, mix, volumes and timer — with one tap.

This app was designed as a sleep aid and nothing more. It is not a therapy, it does not treat autism or ADHD, and nothing here replaces advice from someone who knows your child. It is a calm, low-stimulation app with a mixer flexible enough that a sensitive child can find a setting they will actually accept — which, if you have been through five rejected sound machines, is not a small thing.