P.0330 Maximum downward slopes of sleep slow waves as a potential marker of attention deficit hyperactivity disorder clinical phenotypes

•EEG analysis of Slow Waves' slope helps differentiate clinical phenotypes of ADHD.•Multiple Anxiety Disorders comorbidity in ADHD is positively associated with the Slow Waves' slope.•Autistic traits in ADHD are positively associated with the Slow Waves' slope.•The Slow Waves' slope in ADHD is negatively associated with multiple syndrome scales at the CBCL.•Associations between the Processing Speed Index (WISC-IV) and the Slow Waves' slope in ADHD are lateralized on the scalp.