ADHD symptoms are associated with decreased activity of fast sleep spindles and poorer procedural overnight learning during adolescence.

ADHD and its subclinical symptoms have been associated with both disturbed sleep and weakened overnight memory consolidation. As sleep spindle activity during NREM sleep plays a key role in both sleep maintenance and memory consolidation, we examined the association between subclinical ADHD symptoms and sleep spindle activity. Furthermore, we hypothesized that sleep spindle activity mediates the effect of ADHD symptoms on overnight learning outcome in a procedural memory task. We studied these questions in a community-based cohort of 170 adolescents (58% girls, mean age = 16.9, SD = 0.1 years), who filled in the Adult ADHD Self-Report Scale (ASRS-v1.1), and underwent an overnight sleep EEG coupled with a mirror tracing task before and after sleep. Elevated ADHD symptoms were associated with weaker fast sleep spindle activity, and poorer overnight learning in the procedural memory test. However, sleep spindles, contrary to the hypothesis, did not mediate the association between ADHD symptoms and overnight learning. Our results showed that a higher level of ADHD symptoms in adolescence is associated with similar alterations in sleep spindle activity as observed in many neuropsychiatric conditions and might contribute to altered synaptic connectivity and sleep fragmentation observed in ADHD.