Nurses introduce the correct sleeping posture for children in Handan City, north China's Hebei Province, March 21, 2017. Tuesday marks the World Sleep Day. (Xinhua/Hao Qunying)
A teacher corrects sleeping postures for children at a kindergarten in Anping County, north China's Hebei Province, March 21, 2017. Tuesday marks the World Sleep Day.(Xinhua/Li Xiaoguo)
A teacher introduces the correct sleeping posture for children at a kindergarten in Anping County, north China's Hebei Province, March 21, 2017. Tuesday marks the World Sleep Day. (Xinhua/Li Xiaoguo)
