Deep Sleep and the Infant Brain: Sensory Decoupling Depends on an Infant’s Sensory Profile
Deep Sleep and the Infant Brain: Sensory Decoupling Depends on an Infant’s Sensory Profile
The study by De Laet, Whitworth, Fincham, Lazar, Bedford, and Gliga (2026) investigates a fundamental aspect of early brain development: how the infant brain disengages from sensory input in order to maintain deep sleep. Using polysomnography and EEG recordings during laboratory naps, the researchers examined how individual differences in infants’ sensory profiles influence their ability to remain asleep in the presence of auditory stimulation.
The findings reveal that sensory decoupling during deep sleep varies across infants. Babies with higher sensory reactivity showed weaker slow-wave activity and lower sleep spindle density, both neural markers that normally help protect the brain from external sensory disturbances during sleep.
These results suggest that individual sensory profiles influence the quality and stability of deep sleep during the first year of life, a critical period for brain development.
Deep Sleep and the Infant Brain
What the Study Demonstrates
To investigate this phenomenon, the researchers studied 44 infants aged 8 to 11 months, including infants with typical developmental likelihood and others with a higher likelihood of autism due to having autistic siblings.
Each infant participated in two laboratory nap conditions:
a baseline nap in a quiet environment
a nap with mild auditory stimulation (tones around 60 dB)
During sleep, the researchers analyzed two EEG features associated with sleep protection:
slow-wave activity (SWA)
sleep spindles
The results showed that:
infants with higher sensory sensitivity exhibited reduced slow-wave activity
they also showed lower sleep spindle density
exposure to auditory stimuli amplified these differences
Interestingly, the auditory stimulation did not necessarily wake the infants. Instead, it altered the microstructure of sleep across the entire nap, suggesting that the brains of more sensory-reactive infants remain more coupled to the external sensory environment even during sleep.
A Decolonial Neuroscience Perspective
From a Decolonial Neuroscience perspective, this study reinforces a key idea: the brain cannot be understood independently from the body and the sensory environment in which development occurs.
Deep sleep depends on the brain’s capacity to filter and regulate sensory input. When this gating mechanism differs across individuals, the experience of sleep also changes.
This observation aligns with the concept of the Damasian Mind, in which mental states emerge from the integration of interoception, proprioception, and environmental perception (Damasio, 2018). Deep sleep can therefore be understood as a state in which the brain must temporarily reduce its coupling with the external sensory territory in order to consolidate memory, support neural plasticity, and regulate physiological states.
Differences in sensory sensitivity may therefore influence how the brain negotiates the balance between connection and disconnection from the environment.
APUS and the Body–Territory During Infant Sleep
The conceptual avatar that helps interpret this study is APUS, representing extended proprioception and body–territory coupling.
During deep sleep, the brain typically reduces its responsiveness to environmental stimuli, creating a state of partial sensory decoupling that allows the organism to enter restorative physiological states.
However, infants with higher sensory reactivity appear to maintain stronger coupling with the surrounding sensory environment, even during sleep.
This means that their brains remain more attentive to the surrounding sensory territory, which may make it more difficult to sustain stable deep sleep.
Connections with Tensional Selves and Functional States
The dynamics observed in the study can also be interpreted through the concept of Tensional Selves, referring to functional states that organize the relationship between the body and its environment.
During sleep:
Zone 1
A transitional state between wakefulness and sleep, where the brain still partially responds to sensory stimuli.
Zone 2
A state of stable deep sleep, characterized by strong sensory decoupling, robust slow waves, and sleep spindles.
Zone 3
A state in which the brain remains excessively coupled to environmental stimuli, preventing the stabilization of deep sleep.
The findings suggest that infants with higher sensory reactivity may have greater difficulty stabilizing deep-sleep states comparable to Zone 2.
DREX Citizen and Environmental Conditions for Development
Although the study focuses on neurobiological mechanisms, it also highlights an important principle: environmental stability strongly influences early physiological regulation.
Infant sleep is particularly sensitive to:
environmental noise
predictability of the environment
emotional and social stability
Within the concept of DREX Citizen, social belonging can be understood through a biological analogy. Just as cells require stable energy to function properly, children require predictable and secure environments for essential biological processes — such as deep sleep — to occur effectively.
More stable environments may therefore support better sensory regulation and healthier neural development.
New Questions for BrainLatam
Do differences in infant sensory profiles influence brain–body synchronization during sleep, measurable through EEG or fNIRS?
Is there a relationship between heart rate variability (HRV) and the capacity for sensory decoupling during sleep?
Do infants exposed to predictable auditory rhythms, such as soft music or maternal voice, show more stable deep sleep?
Could early development of sensory gating mechanisms predict later neurocognitive trajectories?
Can early sensory interventions strengthen the brain’s ability to filter environmental stimuli during sleep?
Possible Experimental Designs
Future studies could combine EEG, physiological monitoring, and environmental measurements to investigate how infant brains regulate the interaction between sensory stimuli and deep sleep.
Another promising direction would involve studying mother–infant interactions during sleep, examining how caregiver presence or proximity influences neural stability during naps.
Researchers could also investigate how predictable auditory rhythms, such as lullabies or maternal speech, modulate slow-wave activity and sleep spindle dynamics in infants with different sensory profiles.
BrainLatam Conclusion
The study by De Laet and colleagues highlights a key principle of early brain development: deep sleep requires the brain to partially disengage from the sensory world.
When this sensory decoupling mechanism is weaker, sleep may become lighter or more fragile, even if its duration appears normal.
From a Decolonial Neuroscience perspective, understanding infant sleep requires examining not only the brain but also the body within its sensory and social environment.
References
De Laet, A., Whitworth, M., Fincham, H., Lazar, A. S., Bedford, R., & Gliga, T. (2026).
Sound asleep: Sensory decoupling during sleep depends on an infant’s sensory profile.
Sleep. https://doi.org/10.1093/sleep/zsag010
Damasio, A. (2018). The strange order of things: Life, feeling, and the making of cultures. Pantheon Books.
