ADHD as a circadian rhythm disorder: evidence and implications for chronotherapy

Attention-Deficit/Hyperactivity Disorder (ADHD) is characterized by difficulties with inattention, hyperactivity, and impulsivity. Recent research suggests a relationship between ADHD and sleep/circadian rhythm disruptions. Up to 80% of adults with ADHD experience insomnia, and a significant portion of children with ADHD also have sleep disturbances.

Evening chronotypes, delayed sleep-wake timing, and later dim-light melatonin onset (DLMO) are common in individuals with ADHD. These circadian abnormalities are often accompanied by irregular cortisol rhythms and smaller pineal gland volume. Treatment with melatonin and bright light therapy has been shown to advance the sleep/wake cycle in ADHD patients, leading to symptom improvement.

The authors propose a behavioral-first clinical approach to address sleep/circadian issues in ADHD patients, including routine screening, phenotypic characterization, and implementing fixed wake times, morning bright light exposure, evening light restriction, and regularized zeitgebers. Further research is needed to determine the effectiveness of these interventions on core ADHD symptoms and to identify optimal circadian-focused protocols.