Sound Sensitivity at Bedtime

Why "just play it softer" isn't sufficient advice

Sound sensitivity is one of the most consistently reported features of autism, and it's the mechanism this app's design leans on hardest. It's also widely misunderstood — including the direction it points in. It isn't only about loud sounds, and turning everything down isn't the whole answer.

How common it is, and what it costs

By parent report, roughly 67% of autistic children show auditory hypersensitivity. Among those children, the consequences are specific and measurable: 79.8% have sleep difficulties, 76.8% have trouble concentrating, 74.8% cover their ears, and 74.6% show visible nervousness in response to sound. Across different studies, hyperacusis — discomfort at ordinary volumes — is measured at 18–69% in autism, against roughly 3–17% in the general population.

The average threshold of discomfort in autistic children and teens seeking help for this was measured around 64 dB — about the loudness of an ordinary conversation. That's meaningfully quieter than what most parents would think of as "keeping it down."

The part that gets missed: it's about sudden, not just loud

A startle-reflex study measured eye-blink response (a standard, objective measure of startle) in 12 autistic children and 28 non-autistic children, ages 6–17, across a range of sound levels. The autistic group showed a significantly larger startle response to quiet sounds (85 dB and below). At louder levels (above 90 dB), there was no meaningful difference between the groups. The autistic children's startle response also peaked later and lasted longer.

Why the brain doesn't always "tune it out"

For most listeners, a sound played continuously in the background gradually fades from conscious attention — a process called habituation. Two studies complicate that assumption for autism specifically: a MEG study found that in boys with autism and sound sensitivity, the brain's electrical response to a repeated sound actually grew rather than shrank, and an fMRI study in autistic adults found reduced adaptation to regularly repeated sounds, correlated with autism severity.

Both of those studies used short, spaced-out sounds — not continuous background noise — so it would be overreaching to say a steady ambient layer definitely behaves the same way. The conclusion the evidence supports is narrower: you can't simply assume a sound will fade into the background the way it might for someone else. That uncertainty is exactly why this app times the sleep session rather than defaulting to indefinite overnight playback, and why the sleep timer's fade-out here defaults to a longer setting than in our other sleep apps.

Safe, practical volume guidance

• Start lower than feels useful. With sensitive hearing, what sounds like faint background to you may already be too much.
• Keep the phone at least 2 metres (about 7 feet) from the bed. Distance does more for safety than the volume dial.
• The 60/60 rule for headphone listening in general: no more than 60% of maximum volume, for no more than 60 minutes at a stretch. The WHO's broader safe-listening guidance points at a similar target, around 75 dB or roughly 60% of maximum.
• Never use headphones or earbuds on a sleeping child. There's no safe way to monitor what's reaching the inner ear once they're on.

Screens make it worse here specifically

A study comparing autistic boys, boys with ADHD, and neurotypical boys (ages 8–17) found that having any electronic device in the bedroom was associated with less sleep across all three groups — but the effect was strongest in the autistic group. One proposed explanation is that autistic children find it harder to disengage from a screen once they're on it, which is a close cousin of the predictability problems discussed on the predictability page.

A more recent study of 358 autistic preschoolers sharpens this further: it wasn't total daily screen time that predicted behaviour problems — it was screen time specifically in the window before bed (p = 0.033), while total daily use showed no such link. Sleep quality partly explained the connection. That distinction — bedtime screen use, not screen use in general — is exactly what this app's Auto Screen Off targets: it doesn't ask a family to give up screens altogether, only to have the screen go dark for the specific window research says actually matters, while the routine continues with sound alone.