Attention-deficit-hyperactivity-disorder (ADHD) is the most frequent psychiatric disorder present in childhood, and sleep-problems are a prominent, pervasive and clinically important feature of ADHD. Our understanding of whether sleep-problems mimic or exacerbate daytime ADHD-symptom expression remains insufficient. Furthermore we lack knowledge about the connection between objective measuring and subjective observations in children with early symptoms of ADHD.

Future research that examines sleep-problems and daily activity in very young children with and without ADHD-like symptoms might help us identify early risk factors and achieve a better understanding of the importance of sleep in ADHD.

To investigate if sleep-problems and activity level during day time is associated with early signs of ADHD.

A sample of 50 preschool children ages 2–3 and their parents recruited in a birth cohort are invited to participate and divided into two groups of 25 cases and 25 controls based on ADHD-symptom score. An actigraph on the child's non-dominant wrist measures sleep and daily activity. Sleep-latency, total sleep time and awakenings are examined. Moderate-to-vigorous-activity (MVPA) is the measure for daily activity. Subjective observations from parents are provided through questionnaires. Furthermore we examine the stability of the sleep problem score from child behavior checklist, which parents fulfilled when their child was 27 months old and again at the age of 5.

The results will be presented at the EPA March 2016 in Madrid.

Results from this study together with other findings of risk factors in the cohort may lead to a preschool ADHD risk-index, which can guide future early intervention.

The authors have not supplied their declaration of competing interest.