Sleep microstructure in attention deficit hyperactivity disorder according to the underlying sleep phenotypes

The analysis of sleep microstructure in attention deficit hyperactivity disorder (ADHD) revealed an under-representation of the EEG slow component during NREM sleep. Previous studies either excluded or did not characterize objectively sleep disorders, which notoriously affect sleep architecture. The present study aimed to investigate the cyclic alternating pattern in a real clinical sample of children with ADHD, in whom sleep disorders could be considered. Twenty-seven consecutively enrolled drug-naïve children (mean age, 10.53 years; nine females) and 23 controls (mean age, 10.22 years; 11 females) underwent a full sleep investigation, including attended video-polysomnography. Visual cyclic alternating pattern analysis was performed in a blinded way. Children with ADHD had one or more sleep disorders (a narcolepsy-like phenotype was found in two cases, sleep onset insomnia in three cases, arousal disorder in one case, movement disorder phenotype in six cases and obstructive sleep apnea in 11 cases, and six children had sleep-related epileptiform discharges). Children with ADHD and normal controls showed a similar microstructure with a cyclic alternating pattern rate of about 50%. Children with obstructive sleep apnea had a significantly higher cyclic alternating pattern rate during stage N3. Despite not reaching statistical differences, a lower cyclic alternating pattern rate and A1 index were found in children without epileptic abnormalities/obstructive sleep apnea. Our analysis might allow differentiation of the "primary form" of ADHD associated with a decrease of NREM instability from those forms associated with sleep apnea and epileptic activity.