There and back again: a current history of sleep medicine.

Sleep science has been a vigorously evolving field over the past 60 years, and the practice of sleep medicine has become increasingly complex with a growing number of tests and treatments. This article briefly traces the history of the field of sleep science over the past three millennia. The foundations of sleep medicine can be traced back to ancient civilizations around the globe. Many philosophers, scientists, and researchers have espoused theories about the causes of sleep throughout the centuries, theories that have become more intricate as our understanding of medicine and neurobiology has continued to advance.