Sleep Spindle Features and Neurobehavioral Performance in Healthy School-Aged Children.

PURPOSE: In adults, central fast-frequency sleep spindles are involved in learning and memory functions. The density of local spindles is higher than global spindles, emphasizing the importance of local plastic neural processes. In children, findings on the association of spindles with cognition are more variable. Hence, we aim to study whether the local spindles are also important for neurobehavioral performance in children. METHODS: We studied the correlations between local (occurring in only one channel: Fp1, Fp2, C3, or C4), bilateral, and diffuse (occurring in all four channels) spindles and neurobehavioral performance in 17 healthy children (median age 9.6 years). RESULTS: Local spindles were not as frequent as bilateral spindles (P-values < 0.05). Central spindle types had significant correlations with sensorimotor and language functions (e.g., the density of bilateral central spindles correlated positively with the Object Assembly in NEPSY, r = 0.490). Interestingly, frontopolar spindles correlated with behavior (e.g., the more bilateral the frontopolar spindles, the less hyperactive the children, r = -0.618). CONCLUSIONS: In children, the local spindles, but also more widespread central spindles, seem to be involved in the cognitive processes. Based on our findings, it is important that ageadjusted frequency limits are used in studies evaluating the frequencies of spindles in children.

Neurobehavioral Outcomes in School-Aged Children with Primary Snoring.

OBJECTIVE: We assess behavioral and attentional problems and neurocognitive functioning in school-aged children with primary snoring (PS). METHODS: Seventeen children with PS and 27 non-snoring peers aged 6-10 years took part in the study. All children underwent a polysomnography (PSG) at the Sleep Laboratory. Snoring was defined by parents and with PSG. Children with obstructive sleep apnea were excluded. The parents completed the Sleep Disturbance Scale for Children. Parents and teachers assessed behavioral and attentional problems with the Child Behavior Checklist and the Conners' Rating Scale-Revised. Neuropsychological assessment included the Wechsler Intelligence Scale for Children and the Developmental Neuropsychological Assessment (NEPSY test). RESULTS: The PS group had significantly more parent-reported internalizing, total, and attentional problems than the control group. Teachers did not report behavioral problems in the PS group. The PS and control groups had equal IQ scores and similar core neurocognitive functions, except for one visuospatial subtest. The PS group had significantly more inspiratory flow limitation and increased diaphragmatic electromyography compared with the controls. Parents reported significantly more daytime sleepiness in the PS group. Daytime sleepiness and snoring time were consistently associated with more behavioral and attentional problems. Flow limitation and more oxygen saturation values under 90% were associated with attentional problems, higher oxygen desaturation index, and lower mean oxygen saturation percentage with reduced language functions. CONCLUSIONS: Snoring with an increase in respiratory effort without apneas and hypopneas and parent-reported daytime sleepiness may be linked to daytime symptoms. School-aged children with PS are at risk for behavioral and attentional problems, but not cognitive impairments.