Sleep-related problems are often documented in children with Autism Spectrum Disorders (ASD). This study examined physical activity as a variable that might influence sleep quality in children with ASD. Ten children, ages 9-16 years, were asked to wear accelerometer devices for 7 days in order to track objective measures of activity and sleep quality. Parents of the children also completed the Child's Sleep Habits Questionnaire and maintained a daily sleep log while their child wore the device. This study demonstrated that though over half of the children were identified as having at least one sleep-related problem, their activity levels were significantly related to their sleep patterns. Specifically, the more physically active children had overall higher sleep quality.