Autism spectrum disorder (ASD) is a common neurodevelopmental disorder, which involves persistent difficulties in social interaction and communication, along with restricted and repetitive patterns of behavior [1]. Beyond the core diagnostic criteria, individuals diagnosed with ASD face various co-occurring difficulties, with sleep disturbances emerging as one of the most prominent. Research indicates that 40% to 73% of children with ASD experience sleep problems compared to the general population [2-4]. Most individuals with ASD experience disruptions in sleep patterns, including difficulties with sleep onset and maintenance, night awakenings, and irregular sleep-wake cycles [4,5]. Additionally, 80% of the parents whose children had been diagnosed with autism reported that their children’s sleeping difficulties caused them to have disturbed sleep [3].

Sleep disturbance in children with ASD extends beyond the night hours and influences daytime functioning and increases core ASD symptoms, including communication difficulties, restricted interests, and repetitive behaviors [6]. Sleep disruptions may contribute to increased levels of challenging behaviors, including irritability, hyperactivity, and aggression, in children diagnosed with ASD [7]. Sleep is considered a crucial factor for optimal development, and is also essential for cognitive function, emotional regulation, and physical restoration, especially during childhood [8,9]. Therefore, the disruption of sleep in children with ASD can also affect mood, cognitive function, and social interactions.

Sleep disturbances in ASD are multifaceted; however, sensory processing difficulties may emerge as a prominent factor, as children with ASD often struggle to tolerate the typical sensory experiences associated with sleep. Sensory processing (SP) refers to the complex neurological processes through which the nervous system receives, organizes, and interprets sensory information from the environment, including touch, sound, sight, taste, and smell [10]. Children with autism frequently present with atypical SP challenges, characterized by hyper-reactivity, hypo-reactivity, and sensory-seeking behaviors across different sensory modalities [11]. Tomchek and Dunn [12] reported that 95% of children with ASD experience challenges in SP, which underscores the widespread prevalence of SP dysfunction among these populations. Preliminary evidence suggests that increased sensitivities or aversions to sensory stimuli may contribute to sleep problems in autistic children. For example, Appleyard et al. [13] reported that SP challenges are related to sleep problems in typical toddlers. Additionally, Tzischinsky et al. [14] found that children with autism aged 3–7 years had sleep disturbances due to their hypersensitivity to touch.

The role of SP abnormalities in contributing to sleep disturbances among children with ASD is an evolving area of interest. However, an extensive understanding of the complex link between specific SP patterns and distinct sleep parameters is lacking. Understanding how SP patterns influence sleep is essential for developing tailored interventions aimed at improving sleep quality and overall well-being of children with ASD. Additionally, cultural factors, such as family expectations, societal norms, and community dynamics, can significantly influence how children with autism sleep [15]. Given the significant influence of cultural factors on the sleep of children with ASD, there is a need for research that examines the relationship between SP difficulties and sleep within specific cultural contexts.

Therefore, this study aims to examine the relationship between SP and sleep disturbances in children aged 3 to 11 years diagnosed with ASD. Specifically, the study focuses on the impact of Dunn’s sensory processing patterns, such as sensory seeking, avoiding, sensitivity, and registration, in contributing to sleep disturbances. The research hypothesizes that SP challenges are significantly associated with increased sleep-related difficulties.

The study obtained ethical approval from the Institutional Ethics Committee of SRM Medical College and Research Centre, with the ethical clearance No: 8493/ IEC/2022. The study employed a quantitative cross-sectional research design to investigate the group of 74 children with ASD aged 3 to 11 years. The participants were selected using a convenience sampling method, adhering to specific selection criteria. The inclusion criteria for participant recruitment included: 1) a diagnosis of ASD and age ranging from 3–11 years, and 2) a score above 70 on the Indian Scale for Assessment of Autism. The exclusion criteria were: 1) children with other specific diagnoses to maintain the focus on ASD and 2) children who are receiving medication for sleep disturbances.

The study involved a total of 74 children diagnosed with ASD. An overview of the sample’s demographic characteristics can be found in Table 1. The participant’s mean age was 5.48 years (standard deviation=2.16), with ages ranging from 3 to 11 years. In terms of gender distribution, 67.6% of the participants were boys, and 32.4% were girls. The majority of the participants had no prenatal complications (81.1%), were delivered through cesarean section (68.9%), and were neither pre-term (90.5%) nor had low birth weight (90.5%). The ISAA scores were used to determine the severity of ASD among the participants, with the majority of children (54.1%) classified as having “mild” ASD, 43.2% classified as “moderate,” and 2.7% classified as “severe” ASD.

To evaluate the connection between SP and sleep in children with ASD, partial Spearman’s rank correlation analyses were performed between quadrants, sensory section, and behavioral section of CSP-2 and different domains of sleep disturbances as measured by CSHQ while controlling for the autism severity (mild, moderate, and severe) as shown in Table 2. The findings suggest that children with different SP patterns show significant associations with multiple sleep disturbances, underscoring the interplay between SP challenges and sleep problems in ASD.

This study investigated the relationship between SP and sleep disturbances among children with ASD aged 3 to 11 years. It adds to the growing body of evidence that challenges with SP can have a significant effect on various aspects of daily functioning, including sleep in children with ASD. The study found that SP patterns, assessed using the CSP-2, are closely associated with multiple domains of sleep disturbances measured by the CSHQ. These results align with previous research suggesting that atypical SP may play an important role in the sleep difficulties often experienced by children with ASD [14,21,22].

This study revealed that the “avoiding” sensory quadrant of CSP-2 showed the strongest link to sleep disturbances, such as sleep onset delay, sleep anxiety, night wakings, parasom­nias, daytime sleepiness, and the total CSHQ score. The significant connection between sensory avoidance and sleep-related problems indicates that children who actively avoid sensory input may experience increased arousal, which disrupts their ability to initiate and maintain sleep. The multiple regression analysis of the CSHQ and the quadrants of CSP-2 highlighted sensory-avoiding behavior as a significant predictor of sleep problems in children with ASD. This is in line with earlier studies that have found that sensory over-responsivity contributes to both anxiety and sleep-related difficulties in children with ASD [21,23].

Children with sensory sensitivity often experience significant sleep disturbances. These children may be more aware of and responsive to environmental stimuli, like sounds or textures, which can interfere with their sleep and contribute to anxiety at bedtime [14]. Additionally, the registration quadrant of Dunn’s model revealed a strong link to sleep problems, likely due to challenges identifying and responding to environmental cues that help regulate the sleep/wake cycle, resulting in sleep disruptions [22].

The study found that difficulties in oral and movement processing are linked to sleep disturbance scores, which aligns with the conclusions of Kosaka et al. [24]. They found that a lower threshold to oral sensory stimuli might contribute to difficulties with falling asleep in children with ASD, possibly due to discomfort during oral hygiene routines (like tooth brushing) or hypersensitivity to oral stimuli at bedtime [24]. Similarly, difficulties in vestibular processing can affect sleep, as children may experience discomfort from postural changes or instability when shifting positions at bedtime. This discomfort can result in increased restlessness and difficulties in both falling asleep and staying asleep [24]. Additionally, touch processing difficulties were strongly correlated with various sleep disturbances, such as sleep anxiety, night wakings, parasomnias, and daytime sleepiness. This supports the earlier findings that identified tactile processing difficulties as significant predictors of poor sleep quality in children with ASD [14,22,25]. In contrast, visual and auditory processing did not show significant correlations with total CSHQ scores, which is consistent with Tzischinsky et al. [14] and Wang et al. [22]. However, this finding differs from Tyagi et al. [26], who reported a link between decreased visual processing scores and higher CSHQ scores. These differences may be due to variations in sample characteristics, cultural contexts, or measurement methods used in the studies.

Several physiological and neurobiological mechanisms may explain the relationship between SP and sleep in children with ASD. A significant aspect is the altered levels of gamma-aminobutyric acid (GABA), a neurotransmitter, in children with ASD, which is associated with changes in SP. These deficits might lead to difficulties in behavior regulation, making it challenging for the child to stay calm and achieve a sound sleep [27].

This study highlights the importance of including SP assessments in the clinical evaluations of sleep problems in individuals with ASD. Due to the strong links between SP, especially sensory avoidance, and sleep disturbances, clinicians need to consider sensory-based interventions, like sensory integration therapy or sensory diets, to improve sleep quality in individuals with ASD [28].

The small sample size in this study may limit the generalizability of the results. Future studies should attempt to incorporate larger and more diverse populations to validate these findings across different groups. Moreover, longitudinal research is required to investigate the directionality of these associations across time. Research should also investigate the impact of specific sensory-based interventions on sleep quality to develop more effective, personalized treatment strategies for individuals with ASD. Another limitation is the dependence on parent-reported questionnaires, like the CSP-2 and CSHQ, which can be affected by response bias, recall bias, and parents’ subjective interpretations of their children’s behavior. To overcome these limitations, future studies should use objective assessment tools to evaluate SP and sleep disturbances. For instance, actigraphy or polysomnography could offer more precise and quantifiable data on sleep patterns and quality.

This study emphasizes the important role that SP difficulties in contributing to sleep disturbances among individuals with ASD. The results indicate that specific SP quadrants from CSP-2–avoiding, sensitivity, and registration—are significantly associated with different aspects of sleep disturbances. Among these, “sensory avoiding” emerges as the significant predictor of overall sleep disturbances, underscoring the vital influence on sleep-related difficulties in individuals with ASD. Additionally, the sensory sections of CSP-2, which include auditory, oral, touch, and movement processing, have been associated with sleep problems in children with ASD. The findings from this study can guide the tailored sensory-based interventions, such as sensory integration therapy, aimed at improving sleep quality and overall well-being for children with ASD by addressing their specific SP challenges.