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 973 practicing sleep medicine doctors. Broken out by state, sleep medicine doctor density in Alabama is 16, in Alaska is 2, in Arizona is 13, in Arkansas is 1, in California is 110, in Colorado is 17, in Connecticut is 18, in Delaware is 6, in District of Columbia is 6, in Florida is 56, in Georgia is 46, in Hawaii is 2, in Idaho is 4, in Illinois is 44, in Indiana is 20, in Iowa is 10, in Kansas is 4, in Kentucky is 28, in Louisiana is 8, in Maine is 5, in Maryland is 27, in Massachusetts is 18, in Michigan is 54, in Minnesota is 18, in Mississippi is 15, in Missouri is 20, in Montana is 2, in Nebraska is 9, in Nevada is 11, in New Hampshire is 10, in New Jersey is 30, in New Mexico is 10, in New York is 78, in North Carolina is 43, in North Dakota is 2, in Ohio is 60, in Oklahoma is 5, in Oregon is 15, in Pennsylvania is 50, in Rhode Island is 9, in South Carolina is 13, in South Dakota is 1, in Tennessee is 33, in Texas is 124, in Utah is 10, in Vermont is 1, in Virginia is 21, in Washington is 21, in West Virginia is 8, and in Wisconsin is 14.