While training at the University of Rochester, he was part of the research team that identified a brain cleaning system, termed the ‘glymphatic system' that clears away wastes such as amyloid beta from the brain during sleep. Iliff's recent studies have shown that the glymphatic system may fail in the aging brain and in the young brain after traumatic brain injury. Research in his lab now focuses on identifying the molecular changes that underlie glymphatic system failure with aging and after trauma, extending these studies into human subjects and clinical populations, and discovering ways to co-opt the glymphatic system to improve drug delivery throughout the brain and spinal cord.