The impact of insomnia disorder on adult attention-deficit/hyperactivity disorder severity: A six-month follow-up study

Background and objectives: The longitudinal relationship between insomnia disorder and adult attention-deficit/hyperactivity disorder (ADHD) has been scarcely investigated. This study aimed to evaluate the relationship between the remission of insomnia disorder and adult ADHD clinical severity, psychiatric and medical comorbidities, and the health-related quality of life (HRQoL) in a 6-month follow-up. Methods: Ninety-two adult patients with ADHD and insomnia disorder (52.2% males; mean age 39.5 +/- 11.0 years) were comprehensively assessed at baseline, 3 months, and 6 months of a follow-up period. The evaluation included semi-structured interviews (for ADHD and comorbidity assessment), the Pittsburgh Sleep Quality Index, Insomnia Severity Index, and Epworth Sleepiness Scale. The diagnosis of ADHD and insomnia disorder was performed according to DSM-5 criteria. At baseline and follow-up, psychoeducation/sleep hygiene and, if necessary, pharmacological were prescribed for insomnia. Results: Eighty-seven patients completed the 6-month follow-up. Insomnia disorder remission was reported in 72.4% of cases and was related to a greater improvement in ADHD symptoms and severity throughout the followup period. Additionally, an improvement in psychiatric comorbidities and better HRQoL were associated with insomnia disorder remission. Conclusion: The current study highlights that the treatment of insomnia disorder in ADHD adult patients may have an important role in the outcome of ADHD therapeutic approaches by reducing their severity.