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.

Methylphenidate (MPH), the first-line medication in children with attention-deficit/hyperactivity disorder (ADHD), 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.

En niños con TDAH con problemas de sueño después de recibir un tratamiento de MPH, la melatonina puede ser un tratamiento eficaz y seguro, independientemente de su sexo, edad y comorbilidades. 

https://www.dovepress.com/effects-of-melatonin-in-children-with-attention-deficithyperactivity-d-peer-reviewed-article-NDT

https://psiquiatria.com/trastornos-infantiles-y-de-la-adolescencia/efectos-de-la-melatonina-en-ninos-con-tdah-con-trastornos-del-sueno-despues-del-tratamiento-con-metilfenidato/