O019 Sleep spindles are reduced in children with Down syndrome and sleep disordered breathing

BACKGROUND: Children with Down syndrome (DS) are at increased risk of sleep disordered breathing (SDB), which is associated with sleep disruption affecting daytime functioning. There is growing evidence that sleep spindles may serve as a sensitive marker of sleep quality. We investigated sleep spindle activity and its relationship with daytime functioning in children with DS compared to typically developing (TD) children matched for SDB severity. METHODS: Children with DS and SDB (n=44) and TD children matched for age, sex and SDB severity underwent overnight polysomnography. Fast or Slow sleep spindles were identified manually during N2 and N3 sleep. Spindle activity was characterised as spindle number, density (number of spindles/h) and intensity (density x average duration) on central (C) and frontal (F) electrodes. Parents completed the Child Behavior Checklist (CBCL) and OSA-18 questionnaires. RESULTS: Spindle number, density, and intensity were lower in the children with DS compared to TD children for F Slow and F Slow&Fast spindles combined (p<0.001 for all). In children with DS, there were no correlations between the density of any spindle type and subscales of the CBCL, however, spindle number, density and intensity for C Fast and C Slow&Fast were negatively correlated with OSA-18 emotional symptoms and caregiver concerns and C Fast number, density and intensity were also negatively correlated with daytime function and total problems. CONCLUSIONS: The reduced spindle activity in the children with DS, indicates sleep micro-architecture is disrupted and this disruption may underpin the negative effects of SDB on quality of life and behaviour.