Effects of melatonin in children with attention- deficit/hyperactivity disorder with sleep disorders after methylphenidate treatment

Purpose: Methylphenidate (MPH), the first-line medication in children with attention-deficit/ hyperactivity disorder (ADIID), is associated with increased risk of sleep disorders. Melatonin has both hypnotic and chronobiotic properties that influence circadian rhythm sleep disorders. This study explores the effectiveness of melatonin in children with ADHD who developed sleep problems after starting MPH. Patients and methods: This study, based on a clinical database, included 74 children (69 males, mean age 11.6 +/- 2.2 years) naturalistically treated with MPH (mean dosage 33.5 +/- 13.5 mg/d). The severity of sleep disorder (sleep onset delay) was recorded at baseline and after a follow-up of at least 4 weeks using a seven-point Likert scale according to the Clinical Global Impression Severity score. Effectiveness of melatonin on sleep (mean dosage 1.85 +/- 0.84 mg/d) after 4 weeks was assessed using a seven-point Likert scale according to the Clinical Global Impression Improvement (CGI-I) score, and patients who scored 1 (very much improved) or 2 (much improved) were considered responders. Results: Clinical severity of sleep disorders was 3.41 +/- 0.70 at the baseline and 2.13 +/- 1.05 after the follow-up (P<0.001). According to the CGI-I score, 45 patients (60.8%) responded to the treatment with melatonin. Gender and age (children younger and older than 12 years) did not affect the response to melatonin on sleep. Patients with or without comorbidities did not differ according to sleep response. Specific comorbidities with disruptive behavior disorders (oppositional defiant disorder or conduct disorder), affective (mood and anxiety) disorders and learning disabilities did not affect the efficacy of melatonin on sleep. Treatment was well tolerated, and no side effects related to melatonin were reported. Conclusion: In children with ADHD with sleep problems after receiving MPH treatment, melatonin may be an effective and safe treatment, irrespective of gender, age and comorbidities.