Babies who are more sensitive to sensory input may have trouble achieving deep, restorative sleep, according to a new study from the University of East Anglia. The research focused on infants with an increased likelihood of autism and explored how their sensitivity to sounds and sensations could affect their sleep quality.
The study found that babies with heightened sensory sensitivity experienced more disrupted deep sleep when napping in noisy environments. Even in quiet rooms, these infants tended to sleep more lightly than others, suggesting that both their individual sensory processing and the environment play roles in their ability to rest deeply.
"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," said Prof Teodora Gliga from UEA's School of Psychology, who led the study. "By monitoring babies' brainwaves, we could see clear differences in how deeply infants slept in response to sound."
Prof Gliga added: "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," she said.
Some participants were considered at higher risk for developing autism because they had older siblings diagnosed with the condition. Dr Anna de Laet, first author on the study and now at King's College London, explained: "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."
Dr de Laet noted: "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 gather data, families visited a laboratory where each baby took two naps—one in silence and one with gentle beeps played at conversational volume every few seconds. Researchers measured brain activity during these naps to assess differences in sleep depth between conditions. Parents also filled out questionnaires about their child's typical behaviors and sensitivities.
A total of 41 babies aged eight to eleven months participated in the final analysis.
Prof Gliga stated: "Reducing noise may help particularly sensitive babies, but it's not enough on its own. Their sleep was still shallower in quiet environments."
She emphasized: "Good sleep is vital for brain development and emotional well‑being, so understanding these differences is key to providing better support for families."
The researchers call for further studies into ways to improve deep sleep among sensitive infants by possibly enhancing the brain's ability to filter out sensory input during rest.
The research was funded by Wellcome and published under the title 'Sound asleep: Sensory decoupling during sleep depends on an infant's sensory profile' in Sleep journal.
