['To examine whether the level of sleep efficiency of children diagnosed with ADHD moderates their performance on the Continuous Performance Test (CPT) while receiving a placebo and while receiving methylphenidate (MPH).', 'Nightly sleep actigraphic assessment during a double-blind, placebo-controlled, crossover clinical study (1 week of 0.5 mg/kg MPH; 1 week of placebo) were obtained on 37 children between 6 and 12 years of age with a DSM-IV diagnosis of ADHD. Subjects were divided into 2 groups based on the mean sleep efficiency score during the placebo condition, with subjects above and below the mean placed in the Poor Sleep Group (PSG) and Good Sleep Group (GSG), respectively.', 'Vigilance testing was conducted in the laboratory; sleep was assessed in the home.', "Sleep was monitored using actigraphy for 2 weeks. In addition, parents were asked to complete nightly sleep logs and a sleep questionnaire. The Conners' Continuous Performance Test (CPT) was used to assess vigilance.", 'Significant interaction of Sleep Group with Medication was found on 1 CPT factor.'] Is performance on the continuous performance test in children with ADHD associated with sleep efficiency?