ABSTRACT Caregivers of children with fetal alcohol spectrum disorders (FASD) often report that their child has problems with sleep. However, despite decades of research on the consequences of prenatal alcohol exposure, sleep behaviors are grossly understudied, even though sleep disturbances may mediate or exacerbate some of the cognitive and emotional effects of prenatal alcohol exposure and could serve as a potential target for intervention. In fact, sleep difficulties are related to neurobehavioral deficits in typically developing populations and may have more robust effects on neurobehavioral functioning among individuals with developmental disorders. We hypothesize that children with FASD will demonstrate greater sleep disturbance compared to controls. We also predict that sleep disturbance will be related to increased emotional reactivity, hyperactivity, aggression, and depression, and greater deficits in executive functioning, memory, and attention. Moreover, preclinical studies indicate that prenatal alcohol exposure can disrupt the clock genes that control circadian rhythmicity at a cellular level. Thus, we hypothesize that clock genes will be expressed differently in children with prenatal alcohol exposure. First, this proposal will examine sleep in children with FASD with both wearable technology and subjective measures. Secondly, the relationship between sleep quality and neurobehavioral outcome will be examined. Finally, as an exploratory aim, we will determine if children with FASD exhibit differential expression of clock genes. These data will allow us to better understand the effects of prenatal alcohol exposure on sleep and lay the foundation for developing targeted interventions that may not only improve sleep, but also have the potential for enhancing functioning in other cognitive and emotional domains as well.