Summary: Infants who show high sensory sensitivity—an early trait often associated with autism—may struggle to reach the deepest, most restorative stages of sleep. New research measuring brain activity during naps finds that although these babies spend a similar amount of time in deep sleep as other infants, the slow brain waves that indicate restorative sleep are smaller and weaker. This suggests their brains remain more reactive to the environment, helping to explain why some neurodivergent babies seem easily disturbed and offering a new perspective for supporting early brain development and sleep health.
Researchers monitored infants’ brainwaves during controlled naps to study how sensory sensitivity affects sleep depth. The findings show a clear difference in sleep quality: highly sensitive infants experience shallower deep sleep, and their sleep is especially vulnerable to disruption by ordinary background sounds. The results highlight a link between sensory processing and the brain’s ability to “decouple” from external input during sleep—an ability that supports memory consolidation, emotional regulation, and healthy brain development.
Key Facts
- Shallower deep sleep: Infants with elevated sensory sensitivity produce smaller, weaker slow waves during deep sleep, indicating less restorative sleep even when total deep-sleep time appears similar.
- Reduced sensory decoupling: Whereas most infants’ brains effectively shut out external stimuli during deep sleep, highly sensitive infants remain partially responsive to sounds such as gentle beeps.
- Noise amplifies disruption: In moderately noisy nap conditions, sensitive infants show greater reductions in deep-sleep quality than their less-sensitive peers.
- Early indicator, not a diagnosis: Sensory sensitivity often appears well before an autism diagnosis is possible; it is a common trait among neurodivergent infants but also occurs in neurotypical children.
- Quiet helps but is not enough: A calm environment reduces disruption, yet sensitive infants still show shallower deep sleep in quiet conditions, suggesting intrinsic differences in neural sensory filtering.
Source: University of East Anglia
Babies with an increased likelihood of autism may find it harder to settle into deep, restorative sleep, a new study from the University of East Anglia reports.
The research team investigated how sensory sensitivity—common in many neurodivergent infants—affects the brain’s ability to maintain deep sleep. They observed that everyday sounds can make it harder for some infants to stay in deeply restorative sleep, and that infants who are more sensitive to sensory input show weaker markers of deep sleep even without noise.
Professor Teodora Gliga of UEA’s School of Psychology, who led the study, explained that parents often report their babies as “easily bothered” by sounds or sensations. By measuring brain activity during sleep, the researchers could see tangible differences in how deeply infants slept when exposed to auditory input.
“More sensitive infants did not spend less time in deep sleep overall,” Prof Gliga said, “but their deep sleep was shallower. The slow waves that characterize that stage were smaller and weaker, indicating reduced depth and quality even when duration was similar.” She added that ordinary environmental sounds were sufficient to further disrupt deep sleep in these infants.
Some infants in the study were considered at elevated likelihood for autism because they had an older autistic sibling. The study used this group, alongside infants without an autistic sibling, to capture a wide range of sensory profiles present early in development.
How the research happened
Dr Anna de Laet, first author and now at King’s College London, noted that autism is highly heritable. The team recruited infants both with and without older autistic siblings to examine early sensory traits that can appear well before a diagnosis is possible. These sensory differences do not mean an infant will develop autism; rather, they help researchers study early neural mechanisms related to sleep.
Families attended a UEA sleep laboratory where each infant completed two nap sessions: one in a quiet room and one in a room with intermittent gentle beeps at roughly conversational volume played every few seconds. During each nap, researchers recorded electroencephalogram (EEG) activity to measure features linked to sleep protection, including slow waves and sleep spindles. Parents also completed questionnaires about their infant’s typical behaviour and sensory responses.
Data from 41 infants aged eight to eleven months were included in the final analysis. The researchers compared sleep microstructure across the quiet and auditory-stimulation conditions and related those measures to caregiver-reported sensory reactivity.
Good sleep ‘vital’ for brain development
Professor Gliga emphasized that while reducing environmental noise can help some infants, it may not fully address shallower sleep in highly sensitive babies. “Good sleep is vital for brain development and emotional well-being,” she said, “so understanding these early differences is essential to offer better support to families.”
The study authors call for further research to explore strategies that might strengthen the brain’s sensory filtering during sleep, potentially improving the depth and restorative quality of sleep for sensitive infants.
Funding: Wellcome
The full study, titled “Sound asleep: Sensory decoupling during sleep depends on an infant’s sensory profile,” appears in the journal Sleep. Additional collaborators included Professor Rachael Bedford (Queen Mary University of London) and Dr Alpar Lazar (UEA).
Key Questions Answered:
A: Not necessarily. Sensory sensitivity can be associated with autism but also occurs in many neurotypical children. This study included infants with autistic siblings to examine hereditary patterns, but sensitivity alone is only one part of development and does not equate to a diagnosis.
A: Reducing disruptive noises is a sensible first step, and it may help some infants. However, the study found that sensitive infants still showed shallower deep sleep even in quiet settings, indicating that internal sensory processing differences also play a role.
A: Deep sleep supports critical brain functions like memory consolidation, emotional regulation, and overall neural development. Persistent disruptions or consistently shallower deep sleep can affect how an infant learns and responds to the world while awake.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by editorial 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. Journal: Sleep. DOI: 10.1093/sleep/zsag010
Abstract
Sound asleep: Sensory decoupling during sleep depends on an infant’s sensory profile
Falling asleep and staying asleep require the brain to gate sensory input effectively. Differences in sensory processing—such as elevated sensory reactivity—have been proposed as a contributor to sleep difficulties seen in autistic individuals. Both sensory and sleep challenges are common in autism and often appear early in life.
This study used polysomnography to examine how infant sensory reactivity influences the ability to maintain sleep in quiet versus noisy nap conditions. Forty-four infants aged eight to eleven months, at typical and elevated likelihood for autism, completed two lab-based nap visits: a baseline visit and an auditory stimulation visit where 60 dB pure tones were played during sleep.
The team measured slow waves and sleep spindles—EEG features linked to the brain’s capacity to protect sleep from sensory disturbance. Caregiver-reported higher sensory reactivity was associated with lower slow wave activity and density across both nap conditions. Under auditory stimulation, infants with higher sensory reactivity showed further reductions in slow wave and sleep spindle density. Analyses comparing pre- and post-stimulus windows indicated that rather than producing immediate event-related disruptions, auditory input and sensory reactivity altered sleep microstructure across the entire nap.
In summary, infants with heightened sensory reactivity experience impaired ability to enter or maintain periods of sensory disconnection during sleep, and this vulnerability is amplified by environmental noise.