Source: Liu K, Sun B, Wang BK, Chen J, Westover MB, Tian FY, Sun H, Kong XJ. (2026). An Electroencephalographic Study of Sleep Spindle and Infraslow Oscillation in Children With Autism Spectrum Disorder. Journal of Sleep Research, 35(4), e70309. DOI: 10.1111/jsr.70309. Open Access (CC BY-NC-ND 4.0).
Sleep spindles are brief bursts of oscillatory brain activity in the sigma frequency range (11 to 16 Hz) that hallmark non-rapid eye movement (NREM) sleep. They are generated by thalamocortical circuits and play a well-established role in memory consolidation, sensory gating, and synaptic plasticity. In recent years, researchers have turned attention to how these microstructural sleep features differ in neurodevelopmental conditions such as autism spectrum disorder (ASD), where sleep disturbances and thalamocortical dysfunction are common. A new open-access study published in the Journal of Sleep Research now provides some of the first spatial mapping of spindle and infraslow oscillation (ISO) abnormalities in very young children with ASD.
Key findings at a glance
- Children with ASD showed significantly greater modulation of spindle frequency by the phase of slow oscillations (SO) at a right frontal electrode (F8), compared with typically developing peers (beta = 0.232, SE = 0.065, p = 0.000789). This effect survived rigorous correction for multiple comparisons.
- An infraslow oscillation peak near 0.02 Hz in sigma-band power was visually identifiable in both groups, including children as young as just over one year of age. No significant group differences in ISO peak frequency or amplitude were found after correction.
- In males with ASD, relative ISO power over posterior and temporal regions correlated positively with autism severity scores on the Childhood Autism Rating Scale (CARS), with effect sizes ranging from r = 0.57 to r = 0.69.
- Spindle density, morphology, and SO-spindle co-occurrence did not differ significantly between ASD and typically developing groups after correction.
Why it matters
This study addresses a significant gap in the literature. Prior work has documented spindle deficits in older children and adults with ASD, but the spatial distribution of these abnormalities was poorly understood due to the limited number of EEG channels used in earlier studies. By employing 32-channel EEG in children aged 1 to 5 years, the authors were able to map regional differences with greater precision. The finding of elevated SO-spindle frequency modulation specifically at a right frontal site suggests focal thalamocortical dyscoordination in early ASD. This aligns with a broader hypothesis that disrupted sleep microstructure may contribute to the neurodevelopmental trajectory of the condition.
The study also contributes to a growing literature on infraslow oscillations, rhythmic fluctuations in the 0.005 to 0.03 Hz range that modulate spindle activity over tens of seconds. In animal models, these oscillations have been linked to the norepinephrine system and glymphatic clearance, but they remain understudied in pediatric populations. The demonstration that an infraslow peak is detectable in toddlers even at 1.05 years of age opens the door to longitudinal studies of how this regulatory mechanism develops.
An exploratory sex-specific analysis revealed intriguing patterns. In males with ASD, higher infraslow power correlated with greater symptom severity. In females, the relationship between SO-spindle modulation and autism severity showed the opposite direction, though the female subsample was small (n = 6) and these findings must be interpreted cautiously.
Study design and participants
The researchers recruited 64 children in Shenzhen, China, with a final analytic sample of 53 children (26 with ASD, 27 typically developing controls; ages 1.1 to 5.1 years). After 5 to 6 hours of partial sleep deprivation to encourage daytime sleep, 32-channel EEG was recorded during natural sleep between 9 AM and 3 PM. Sleep staging followed AASM pediatric guidelines. Spindle detection used a validated wavelet-based algorithm, and infraslow oscillations were analyzed through multitaper spectral estimation of sigma-band power time series.
Bottom line
Altered slow-oscillation spindle coupling at a right frontal scalp location is a spatially specific marker of sleep microstructure differences in young children with ASD. Infraslow oscillations, while not differing globally between groups, carry sex-specific associations with clinical severity. These findings point to disrupted thalamocortical coordination as an early feature of ASD and highlight the value of dense-array EEG in pediatric sleep research.
Reference: Liu K, Sun B, Wang BK, et al. An Electroencephalographic Study of Sleep Spindle and Infraslow Oscillation in Children With Autism Spectrum Disorder. J Sleep Res. 2026;35(4):e70309. doi:10.1111/jsr.70309.