Borderline intellectual functioning and sleep: the role of cyclic alternating pattern.

In the clinical literature there are few specific studies about the relationship between cognition processes and sleep during childhood. In addition, milder deficits in general intellectual capacity have received less attention relative to major cognitive dysfunctions (such as the genetic or environmental basis of mental retardation), especially concerning the low normal and borderline status. Sleep could play a key role in multiple intellectual abilities such as memory, executive functions, and school performances. Aim of our study is to assess the sleep macrostructure and NREM instability (cyclic alternating pattern) and their relationship with IQ in a sample of subjects with borderline intellectual functioning (BIF). The DSM-IV defines BIF as a total intelligence quotient (TIQ) ranging between 71 and 84. Intellective functioning was assessed using the Italian version of Wechsler Intelligence Scale for Children-Revised (WISC-R), a well validated test for the developmental age between 6 and 16. For this study, 12 BIF and 17 healthy children, matched for sex and age, underwent an overnight PSG recording. Macrostructural sleep and CAP analysis were also performed. To our knowledge, this study represents the first attempt to evaluate sleep architecture and NREM instability organization in children with BIF. Findings from this investigation evidence that BIF presents alterations in both macro- and microstructural sleep architecture, with an interesting statistical significant correlation with IQ.