Pediatric Sleep Disorders and Special Educational Need at 8 Years: A Population-Based Cohort Study

Abstract

Pediatric sleep disorders result in disrupted, inefficient, and inadequate sleep.^1,2 The most prevalent and pernicious are behavioral sleep problems (BSPs) and sleep disordered breathing (SDB). Both may affect brain development and cause neuronal damage, particularly during critical early development periods.^1–3 Slow wave sleep, the most restorative form of sleep, is largely governed by the frontal cortex, which mediates higher functions, such as decision-making, ambition, and emotional regulation. Disrupting this restorative process via either sleep fragmentation or hypoxemia may affect frontal cortex functioning and lead to aspects of the behavioral phenotype seen with childhood obstructive sleep apnea.^1,2,4

BSPs, characterized by inadequate and fragmented sleep, affects behavior^5,6 and cognition^5–7 and language development.⁸ Similarly, SDB is linked to delayed development,⁹ speech-language impairments,^10,11 and adverse behavioral^2,12 and cognitive^2,13,14 effects. Thus, both disorders can affect school functioning and educational need, in addition to being 2 to 3 times as prevalent among children with developmental delay or disability versus the typically developing child.¹⁵ In the United States, 3 million 6- to 21-year-olds receive special education for conditions associated with sleep disorders (ie, developmental delay, learning disability, or autism); 40% to 80% also have attention-deficit disorder/attention-deficit hyperactivity disorder.¹⁶

While sleep disorders in early childhood may affect special educational needs, just a few studies have analyzed this association. Parents of children in Spain (mean age 11–12 years) in special versus mainstream schools reported significantly higher rates of both BSPs (32.3% vs 10.5%) and SDB (26.8% vs 5.7%),¹⁷ affirming results of an earlier UK study of 4- to 12-year-olds from special versus mainstream educational venues for both BSP (23.8% vs 11.6%) and SDB (19.8% vs 9.0%).¹⁸ An Australian study of 6- to 15-year-olds found similar results, although a low response rate, small sample size, and poor matching¹⁹ limit generalizability.

This is the first prospective, population-based study of the associations between SDB and BSPs throughout early childhood and effect on later special education need (SEN). Given the dynamic, multisymptom expression of SDB’s hallmark symptoms (snoring, apnea, and mouth-breathing) SDB was examined as a combined trajectory of these symptoms. This is a secondary analysis of observational data collected during the peak period in the development of SDB and BSPs, in a cohort of >11 000 children. The study had 2 specific research questions. Is cumulative report of BSP across 4 intervals of ∼12 to 15 months from 18 to 57 months of age associated with an increased likelihood of an SEN determination at 8 years of age? Similarly, are SDB symptom trajectories, or clusters, from 6 to 57 months of age associated with a greater likelihood of SEN at 8 years of age?

Methods

Assessment of SDB and Sleep Problems

SDB Symptoms

Parents reported on their child’s snoring, mouth-breathing, and apnea at 6, 18, 30, 42, and 57 months of age in response to ALSPAC’s mail questionnaires. ALSPAC's Likert scaled items are similar to items validated against polysomnography data; objective sleep evaluation measures were unavailable. Snoring was assessed with the question: “Does she snore for more than a few minutes at a time?” Mouth-breathing was assessed with the item: “Does she breathe through her mouth rather than her nose?” Witnessed apnea was assessed with the question: “When asleep, does she seem to stop breathing or hold breath for several seconds at a time?”

We derived a series of unique (ie, statistically distinct) patterns of these SDB symptoms across the 5 time points via a methodology reported elsewhere.²⁴ Clusters were derived for children with SDB measures at ≥2 of these 5 time points. Briefly, this process yielded 5 unique symptom patterns, or clusters (see Fig 1 A–E), depicting the prevalence of snoring, mouth-breathing, and apnea in SD or z scores, at 6, 18, 30, 42, and 57 months of age.

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FIGURE 1

SDB clusters of combined apnea (AP), snoring (SN), and mouth-breathing (MB) in sample from 6 to 57 months of age.

These 5 clusters classified children as (1) normals, asymptomatic throughout (37% of sample); (2) peak at 6 months, all 3 symptoms peak at 6 months but abate thereafter (19% of sample); (3) peak at 18 months, all 3 symptoms peak at 18 months but lessen thereafter (17% of sample); (4) worst, elevated symptom levels beginning at 18 months that remain high, with a 30-month peak (9% of sample); and (5) late symptom, modestly elevated symptoms first appear at 42 months (18% of sample).

BSPs

At the 18-, 30-, 42-, and 57-month questionnaires, parents were asked 7 items about their child’s sleep. Most pertained to BSPs in the past year (except at 30 months when no recall period was given). Items included whether (yes/no) the child refused to go to bed, regularly woke early, regularly had difficulty sleeping, regularly had nightmares, regularly got up after being put to bed, regularly woke in the night, and regularly got up after a few hours. As in previous ALSPAC analyses,^25,26 we combined these into an index. We applied a cut-off score of ≥5 of these 7 items as a BSP, given that 15%, 27%, 24%, and 21% of the sample responded affirmatively to ≥5 of the 7 items at 18, 30, 42, and 57 months, respectively, consistent with previously published prevalence rates.^27,28 These items were, appropriately, not assessed at 6 months.

Results

Discussion

This is the first population-based study of the association between respiratory-related (SDB) and behavioral (BSP) sleep problems, throughout early childhood, and SEN. Children with a history of BSPs and of SDB in the first 5 years of life were more likely to have an SEN at 8 years of age; even controlling for 16 putative confounders, BSPs were associated with a 7% increased odds of SEN, for each ∼1-year interval. Thus, for example, children with a BSP in at least 2 of the 4 intervals (∼1 of 5 children) had a 15% increased likelihood of SEN. SDB, overall, was associated with a near 40% increased odds of SEN. Children with the worst SDB symptoms were 60% more likely to have an SEN. Sleep problem effects remained significant, even after controlling for IQ, which itself was associated with five- to sixfold increased odds of SEN for both BSPs and SDB. Residual confounding is possible. Specifically, children with underlying neurodevelopmental issues, who are more likely to have SENs, may indeed have more sleep problems. However, given the persistence of sleep problem effects in analyses controlling for multiple putative confounders including IQ, such confounding is unlikely to negate our findings.

Our study differs from the few publications on sleep problems and SEN, in several ways. First, earlier work compared children from specialized versus mainstream schools.^18,19,46 In contrast, we use a population-based approach. Correspondingly, we applied the inclusive SEN designation, rather than the narrower “statement of SEN,” most applicable to children in specialized schools. Second, in contrast to earlier work, our longitudinal cohort study's strengths include large sample size, control for multiple potential confounders, and ability to examine temporal relationships and estimate effects. Previous cross-sectional work analyzed data from ∼100 children or fewer from specialized schools, with limited control for confounders. Third, our work assesses SDB and BSP from infancy through 5 years of age, the peak period for both disorders,^27,47 enabling us to predict cumulative effects during this vulnerable period on later SEN.

Several population-based studies have examined cognitive and academic outcomes (ie, not special education) with mixed results. In 1 study, school-aged children with objectively measured mild SDB did no poorer on most intelligence measures assessed,⁴⁸ in contrast to most research linking SDB to poorer academic performance,^12,14 while in another, objectively measured SDB was significantly associated with cognitive outcomes.⁴⁹ Regarding BSPs, our findings differ from an Australian study finding no concurrent or longitudinal association between “sleep problems” and cognitive outcomes measured at 4 to 5 and 6 to 7 years of age.⁵⁰ In that study, “sleep problems” was defined by just 1 item (ie, whether the parent considered the child to have a sleep problem [none, mild, moderate, severe]), in contrast to our scale-based measure of 7 specific sleep behaviors.

Regarding school outcomes of interventions, adenotonsillectomy to treat SDB is associated with improved neurocognition among 4-year-olds^51,52 and school performance among the lowest performing first graders.⁵³ Limited data are available on school-related outcomes of BSP interventions, despite their known efficacy among young children.^54–57 The 1 published randomized controlled trial did not find improved learning outcomes among 5- to 6-year-olds identified via school screening. Authors posit that the brief instrument that was used may have been insufficiently sensitive to detect changes in skills (eg, working memory) that affect school outcomes or that learning effects might lag beyond the study’s 6-month follow-up.⁵⁸

This study has several limitations. First, neither sleep problem was assessed with validated pediatric sleep questionnaires,^18,19,46 in part, because none were available at the time.⁵⁹ Still, the SDB items are similar to those validated against objective measures,^60–64 while the clusters themselves may better capture the dynamic, multisymptom expression of SDB.²⁴ Our BSP measure corresponds to one used in earlier ALSPAC analyses.^25,26 Second, ALSPAC data did not specify the disabilities that qualified a child for SENs. At the time, the bulk of classifications were for learning versus socioemotional or physical disorders.²¹ In contrast, “behavioral, emotional, and social difficulty,” “speech, language, and communication difficulty,” and “autism spectrum disorder” are now more prevalent among those with SENs, compared with when our study’s SEN outcomes data were collected.⁶⁵ Given overlap between the functional effects of these disabilities and sleep disorders,⁶⁶ our effect sizes may actually be underestimates based on present SEN classifications.

Findings presented here strongly support an association between early childhood sleep problems and later SEN, on a population basis. This highlights the need for early screening, because early treatment is often effective for SDB⁶⁷ and BSPs.⁵⁶ The magnitude of potential benefit from early screening and treatment is greatest for young children with behavioral, cognitive, and language delays/disabilities, because sleep disorders affect functioning in these areas. Currently, US-based early intervention programs do not systematically screen for sleep disorders,⁶⁸ which are underdiagnosed in routine pediatric care.^69,70 Future research should focus on timely and systematic screening and on testing potential interventions, particularly for BSPs, among young children at risk for developmental delay/disability.

Acknowledgments

Glossary

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