One year old baby crying at night, mainly consider the following two reasons: 1, if the daytime frightened or excessive play, too much excitement will affect the night sleep, resulting in the child crying at night. 2, be alert to whether there is vitamin D deficiency rickets, vitamin D deficiency rickets children will be irritable, irritable, crying, sleep at night and so on. At this time, it is recommended that appropriate vitamin D supplementation, the dose can be appropriately increased, but also can give the child calcium supplements, can quickly relieve the symptoms. During the daytime to increase the time of outdoor activities, daily sunshine time of 1-2 hours, can promote their own vitamin D production.