Summary: For babies with a higher likelihood of autism, “quiet” might not be quiet enough. A new study reveals that infants with high sensory sensitivity struggle to achieve deep, restorative sleep—even in peaceful environments.
By monitoring brainwaves, researchers found that while these babies spend the same amount of time in “deep sleep” as others, the quality of that sleep is significantly shallower. Their brain’s slow waves are weaker, indicating a failure to fully “decouple” from the sensory world. This discovery helps explain why neurodivergent infants are often “easily bothered” and provides a new lens for supporting early brain development.
Key Facts
- Shallower Deep Sleep: Highly sensitive infants have smaller and weaker slow waves during deep sleep, meaning their rest is less restorative even if the duration is normal.
- Sensory Decoupling Failure: Most brains “shut out” the world during deep sleep. In sensitive infants, the brain remains partially reactive to external sounds, like gentle beeps.
- Impact of Noise: When napping in even moderately noisy environments, the deep sleep of these infants is considerably more disrupted than that of their less-sensitive peers.
- Early Predictor: Sensory sensitivity is a common trait in neurodivergent infants and often emerges well before a formal autism diagnosis (which typically happens around age three).
- Beyond Noise Reduction: While a quiet room helps, these infants still experience shallower sleep in perfect silence, suggesting an internal “wiring” difference in how they process sensory input.
Source: University of East Anglia
Babies with an increased likelihood of autism may struggle to settle into deep, restorative sleep, according to a new study from the University of East Anglia.
Researchers studied the link between sleep and sensory sensitivity, which is common in neurodivergent infants.
They found that when babies with this trait napped in a noisy environment, their deep sleep was considerably disrupted.
But even in a quiet room, those with high sensory sensitivity still slept more lightly – suggesting that both their unique sensory wiring and their surroundings influence how well they rest.
The work reveals important clues about why some babies, especially those who are highly sensitive to sensory input, are more likely to struggle to achieve restorative sleep.
Prof Teodora Gliga, from UEA’s School of Psychology, who led the study, said: “Many parents tell us their baby seems ‘easily bothered’ by sounds or sensations and we are now beginning to see how that sensitivity can affect their sleep.
“By monitoring babies’ brainwaves, we could see clear differences in how deeply infants slept in response to sound.
“More sensitive infants didn’t spend less time in deep sleep – their deep sleep was simply shallower. The slow waves that define this stage were smaller and weaker, showing that while the duration was similar, the depth and quality of their sleep were reduced.
“Our results show that even everyday sounds can make it harder for some babies to stay in deep sleep, especially those with naturally heightened sensory responses.”
Some babies in the study were at higher likelihood of developing autism, not because they show diagnosable features at such a young age, but because they have an older autistic sibling.
How the research happened
Dr Anna de Laet, first author on the study, and now at King’s College London, said: “Autism is a highly heritable condition. We included infants both with and without an older autistic sibling to capture a wide range of sensory sensitivities, which are common in autism and emerge early in development, often well before a diagnosis is possible.
“These sensitivity traits don’t mean a baby will develop autism, which we can’t diagnose reliably before the age of three, but they help us study how early sensory differences might shape sleep in infancy.”
To understand these patterns, families visited the UEA sleep lab, where each baby completed two naps – one in a quiet room and one in a room where gentle beeps, about as loud as a normal conversation, were played every few seconds.
Researchers recorded babies’ brain activity during sleep and compared sleep depth between the two conditions.
Parents also completed questionnaires about their baby’s typical behaviours and sensory sensitivities, which could be linked to their sleep quality.
A total of 41 babies between eight and 11 months contributed to the data for the final analysis.
Good sleep ‘vital’ for brain development
Prof Gliga said: “Reducing noise may help particularly sensitive babies, but it’s not enough on its own. Their sleep was still shallower in quiet environments.
“Good sleep is vital for brain development and emotional well‑being, so understanding these differences is key to providing better support for families.”
The authors highlight the need for further research into how deep sleep might be better supported in these infants, potentially by strengthening the brain’s ability to filter sensory input during sleep.
Funding: This study was funded by Wellcome.
‘Sound asleep: Sensory decoupling during sleep depends on an infant’s sensory profile’ is published in the journal Sleep.
Additional collaborators: Prof Rachael Bedford, Queen Mary University of London and Dr Alpar Lazar, UEA.
Key Questions Answered:
A: Not necessarily. Sensory sensitivity is a trait that can be linked to autism, but it also exists in many neurotypical children. This study looked at infants with autistic siblings to understand the hereditary nature of these patterns, but sensitivity alone is just one piece of a much larger developmental puzzle.
A: Reducing noise is a great first step, but the study found that sensitive babies still had shallower sleep in quiet rooms. The goal for future research is to find ways to help the brain “strengthen” its ability to filter sensory input during sleep.
A: Deep sleep is the “clean-up and filing” phase for the brain. It’s vital for memory consolidation, emotional regulation, and overall brain development. If sleep is consistently shallow, it can affect how a baby processes the world when they are awake.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this autism and sleep research news
Author: Jordan Bacon
Source: University of East Anglia
Contact: Jordan Bacon – University of East Anglia
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Sound asleep: Sensory decoupling during sleep depends on an infant’s sensory profile” by Anna De Laet , Morgan Whitworth , Hope Fincham , Alpar S Lazar , Rachael Bedford , Teodora Gliga, the SNOOSE team. SLEEP
DOI:10.1093/sleep/zsag010
Abstract
Sound asleep: Sensory decoupling during sleep depends on an infant’s sensory profile
Initiating and maintaining sleep requires gating of sensory input. Sensory processing differences, such as elevated sensory reactivity, have emerged as a potential driver of sleep difficulties in autism. Both sensory and sleep difficulties are prevalent in autistic individuals and emerge early in development.
Here, we use polysomnography to understand how infant sensory reactivity affects the ability to maintain sleep in a quiet or noisy environment.
Forty-four 8- to 11-month-old infants at typical and elevated likelihood for autism participated in a lab-based nap study consisting of two counterbalanced visits, a baseline and an auditory stimulation condition. In the stimulation condition, 60 dB pure tones were played during sleep.
We measured slow waves and sleep spindles, electroencephalogram features previously linked to the ability to protect sleep from sensory disturbance. We show that higher caregiver-reported sensory reactivity was significantly associated with lower slow wave activity and density, across both nap conditions.
In the stimulation condition, infants with elevated sensory reactivity had even further decreased slow wave density and lower sleep spindle density. Comparisons of pre- and poststimulus windows showed that, rather than triggering immediate event-related disruptions, auditory input and sensory reactivity alter sleep microstructure across the longer timescale of the entire nap.
Thus, highly reactive infants experience disruptions in their ability to enter or maintain periods of sensory disconnection, accentuated by the presence of auditory noise.
