Sleep medicine deals with the causes, diagnosis and treatment of sleep disorders. A sleep medicine physician treats problems such as sleep apnea and snoring, insomnia and narcolepsy. Sleep apnea is when a person actually stops breathing for a few seconds during sleep, and is usually accompanied by loud snoring. Narcolepsy is a disorder of the central nervous system, and is characterized by excessive daytime sleepiness, and a tendency to sleep at inappropriate times, even if the person gets adequate nighttime sleep. Also considered sleep disorders are periodic limb movements and restless legs.

Treatment includes overnight study in a sleep center, where technicians observe, monitor, and analyze brain activity, respiratory function, muscle function and other variables that help diagnose complex sleep disorders. Sometimes a physician may fit a patient may with a device to measure a person's activity, their environmental temperature, light levels and mood state, all recorded by a computer the size of wrist watch. This allows the physician to get objective, accurate data on the patient's daily life, and help to assess sleep problems.

Doctor density varies by specialty and location. The United States has 987 practicing sleep medicine doctors. Broken out by state, sleep medicine doctor density in Alabama is 15, in Alaska is 2, in Arizona is 14, in Arkansas is 1, in California is 113, in Colorado is 15, in Connecticut is 17, in Delaware is 7, in District of Columbia is 5, in Florida is 60, in Georgia is 44, in Hawaii is 2, in Idaho is 4, in Illinois is 43, in Indiana is 20, in Iowa is 10, in Kansas is 5, in Kentucky is 29, in Louisiana is 10, in Maine is 5, in Maryland is 26, in Massachusetts is 19, in Michigan is 52, in Minnesota is 18, in Mississippi is 17, in Missouri is 20, in Montana is 2, in Nebraska is 8, in Nevada is 10, in New Hampshire is 10, in New Jersey is 29, in New Mexico is 8, in New York is 77, in North Carolina is 45, in North Dakota is 2, in Ohio is 61, in Oklahoma is 5, in Oregon is 13, in Pennsylvania is 48, in Rhode Island is 8, in South Carolina is 16, in South Dakota is 2, in Tennessee is 34, in Texas is 123, in Utah is 11, in Vermont is 1, in Virginia is 21, in Washington is 22, in West Virginia is 9, and in Wisconsin is 13.