Peter Y. Liu MBBS (Hons I) PhD FRACP is an investigator at The Lundquist Institute, Professor of Medicine in Residence at the David Geffen School of Medicine at University of California – Los Angeles (UCLA), and an endocrinologist at Harbor-UCLA Medical Center. He obtained his medical and doctoral degrees from the University of Sydney, and completed endocrine training at Royal Prince Alfred Hospital and a postdoctoral fellowship at Mayo Clinic, Rochester MN. He is the immediate past president of the International Society of Andrology, and his research examines how sleep disturbances and circadian misalignment impair cardiometabolic health and male fertility, and dysregulates the male gonadal axis causing hypogonadism. He has published over 110 original research papers, and 40 textbook chapters.