Sleep medicine is a medical specialty or
subspecialty devoted to the diagnosis and
therapy of
sleep disturbances and
disorders. From the middle of the 20th century, research has provided increasing knowledge and answered many questions about sleep-wake functioning. The rapidly evolving field has become a recognized medical subspecialty in some countries. Dental sleep medicine also qualifies for
board certification in some countries. Properly organized, minimum 12-month,
postgraduate training programs are still being defined in the United States. In some countries, the sleep researchers and the
physicians who treat patients may be the same people.