Significant sleep dysregulation in a toddler with developmental delay

Derrick's parents made an appointment with a new pediatrician for a second opinion about disordered sleep. Now 22-months old, he was evaluated at 18 months of age for developmental delay when he was found to have "a regulatory disorder associated with delays in language and motor development, hypotonia and significant sleep problems." The parents are now most concerned about his sleeping pattern. Prolonged sleep onset and frequent night awaking occur each night since 6-months of age. These problems are more severe in the past few months when he awakes screaming and cannot be settled. The awakening episodes occur 2 to 4 times each night when "he screams and thrashes his body for up to an hour." Daytime tantrums increased. After the parents read a book about sleep in young children, they provided a calm atmosphere at bedtime including a dark room and singing a quiet lullaby. When these changes did not alter sleep, they purchased a vibrating mattress which was also unsuccessful. Derrick was born full term after an uncomplicated prenatal and perinatal course. He sat at 10 months, crawled at 12 months, and walked at 18 months. He currently drinks from a sippy cup and he can use a utensil to eat. He has few words saying only "no" and "mama" in the past month. Imitation of some words occurred recently. He has responded to simple directions in the past 2 months. Derrick passed the newborn audiology screen. He does not have difficulty swallowing and he does not drool. He plays with many different toys and he plays in parallel with his older brother who also experienced delays in motor and language development. His brother is now doing very well in school. There is no family history of cognitive delay, seizure disorder, cerebral palsy, early developmental delay (other than the brother) or a significant sleep problem.P hysical examination: head circumference, length and weight (75th percentile). He had mild generalized hypotonia, mild weakness, 2+ symmetrical deep tendon reflexes, and absence of ankle clonus. His gait was slightly wide based, steady, and without a limp. Neither ataxia nor drooling was observed. He was easily engaged in play with the examiner without evidence of irritability. The remainder of the examination was normal.