A teacher introduces the correct sleeping posture for children in a kindergarten in Xiajiang County, east China's Jiangxi Province, March 20, 2017. Tuesday marks the World Sleep Day. (Xinhua/Chen Fuping)
A teacher introduces the correct sleeping posture for children in a kindergarten in Xiajiang County, east China's Jiangxi Province, March 20, 2017. Tuesday marks the World Sleep Day. (Xinhua/Chen Fuping)