Abstract
Objective: The aims of this current study were to: (i) examine the natural history of snoring and other sleep disordered breathing (SDB) related symptoms from age 3 to 7 years; (ii) examine the concurrent relationship between SDB and academic performance of 6-year old children and explore potential pathways linking SDB to academic performance; (iii) investigate whether parent-reported habitual snoring at age 3 predicts later academic performance and behavioural outcomes at age 7.
Methods: Parent/s of children (n = 839) who returned a completed Age 3 Community Survey (conducted in 2008 by Dr. Amelia Gill) were re-contacted via mail four years later when children were aged 6-8 years, and asked to complete a Follow-up Survey. This follow-up survey included questions regarding their child’s sleep, academic performance and behavioural adjustment. A subgroup of 170 children from the survey sample were involved in a longitudinal study examining links between SDB, early learning and behavioural adjustment in 3- and 4-year olds. As part of the current research, these children were re-assessed at age 6 (n = 163, mean age 6.3 years) (this study was also known as the Academic Assessment Phase). SDB was assessed through parent-reported history of symptoms, and physical examination of features related to SDB. Children’s neurocognitive functioning and academic performance was assessed using researcher-administered standardised tests, and parent- and teacher-ratings.
Results: At follow-up (age 7), habitual snoring was prevalent in 9.2% of the sample, similar to the 11.3% reported at age 3. However, habitual snoring changed over time; some children (36.2%) remained habitual snorers over the follow-up period, while some others were no longer snoring habitually. In addition, a small group of children (5.3%) started habitual snoring since the Age 3 Community Survey. Additionally, history of habitual snoring at age 3 predicted small but statistically significant unique variance in parent ratings of literacy outcomes and working memory functioning at age 7, even after controlling for important child socio-demographic and health correlates.
Findings from the Academic Assessment Phase at age 6 revealed statistically significant correlations between SDB severity and several cognitive functioning measures (r = -.21 to -.26, p < .01), ratings of executive functioning difficulties (r = .25 to .32, p < .01), literacy and numeracy outcomes (r = -.21 to -.25, p < .01), and rating of academic performance (r = -.23, p < .01). Using a structural equation modeling (SEM) approach, indirect paths between SDB and academic performance were found, in which SDB was found to be directly related to domains of executive functioning, verbal comprehension and communication, and nonverbal reasoning; both verbal and nonverbal composites were predictive of academic performance. General pattern of findings remained even when child’s gender and Deprivation Index was taken into account, respectively.
Conclusion: The current findings highlight the dynamic nature of sleep-disordered breathing in children, where related-symptoms can develop, remain present or resolved at different stages of childhood. Findings from this research also suggest that pathways from SDB to poorer academic performance were indirect, and mediated through children’s verbal and nonverbal abilities. Additionally, history of habitual snoring in preschool years were predictive of children’s later literacy achievement and working memory functioning.