PROJECT SUMMARY/ABSTRACT Tuberous sclerosis complex (TSC) is a relatively common genetic disorder, which features hamartoma or tumor growth in multiple organs, including the brain, and causes a variety of neurological and neuropsychiatric symptoms, including epilepsy, intellectual disability, and autism. Mutation of the TSC1 or TSC2 genes leads to hyperactivation of the mechanistic target of rapamycin (mTOR) pathway, which drives tumor growth and epileptogenesis in TSC. Epilepsy occurs in up to 90% of TSC patients and is intractable to treatment in the majority of cases, often leading to life-long disabling seizures. Sleep disorders are also a common occurrence in TSC and a significant source of decreased quality of life for the patient and family members/caregivers. Independent of TSC, there is a strong association between epilepsy and sleep, with seizures often arising more frequently out of sleep, but the mechanistic basis for this relationship is poorly understood and a link between sleep and seizures in TSC has not been thoroughly investigated. We have recently identified an abnormal sleep phenotype in a mouse model of TSC (Tsc1GFAPCKO mice) that may at least in part relate to an mTOR-dependent increase in hypothalamic orexin expression. In this grant proposal, we propose to investigate the phenomenological and mechanistic relationship between epilepsy and sleep in Tsc1GFAPCKO mice, which also have progressive seizures, as well as in another mouse model of TSC and an acquired epilepsy model. We hypothesize that seizures occur more commonly in sleep in Tsc1GFAPCKO mice. Furthermore, we hypothesize that epilepsy in these mice are at least partly caused by an mTOR-dependent increase in hypothalamic orexin protein translation and will be responsive to treatment with an orexin antagonist. This work is innovative in investigating the relationship between sleep and seizures in TSC and identifying a potential role of hypothalamic orexin in epilepsy. The findings from these studies may have strong impact and translational applications for developing novel therapies for epilepsy in TSC, in particular orexin antagonists. As TSC is often viewed as a model genetic disorder for epilepsy and mTORopathies in general, this project may ultimately have relevance to epilepsy related to other causes.