According to the Mayo Clinic, the field of medicine related to sleep is known as polysomnography. As HealthCommunities.com explains, a doctor with education and training in the field of sleep medicine is known colloquially as a sleep specialist.
WebMD explains that sleep specialists generally work out of clinics known as sleep centers, many of which receive accreditation from the American Academy of Sleep Medicine (AASM). Individual doctors can also receive certification from the American Board of Sleep Medicine (ABSM). HealthCommunities.com cites that an estimated total of 40 million people in the United States are affected by some type of sleep disorder.