Sleep Medicine as a subspecialty is taking off, with new sleep clinics opening up around the country and new imaging modalities giving way to improved understanding of the sleep - wake cycle. Sleep and Psychiatry are very closely linked; in fact, over half of insomnia complaints come from patients with psychiatric comorbidities. 80% of patients with mood disorders have sleep-related complaints. Other disorders very commonly associated with sleep related complaints include major depressive disorder, bipolar disorder, general anxiety disorder, PTSD, and substance abuse.