Sleepy Eye is a small city in rural Brown County, Minnesota, United States. The city is named after a famed local Dakota chief from the 1…Sleepy Eye is a small city in rural Brown County, Minnesota, United States. The city is named after a famed local Dakota chief from the 1800s. The population was 3,599 at the 2010 census. Sleepy Eye took its name from Sleepy Eye Lake, which was named after Chief Sleepy Eye, who was known as a compassionate person with droopy eyelids. The chief was one of four Sioux Native Americans chosen to meet President James Monroe in 1824 in the nation's capital. Later, Sleepy Eye was an integral player in the 1851 signing of the Treaty of Traverse des Sioux, which gave all the land but a 10-mile swath on each side of the upper Minnesota River to the U.S. government. His recommendations to traders led to the successful settlement of Mankato, away from flood areas, and the chief eventually settled his people near the lake now known as Sleepy Eye Lake.