Nine-month-olds sleep 10-12 hours a day Sleeping time varies from age to age, and the younger the child, the longer the sleeping time. Adequate sleep is a necessary condition for the growth and development of children, nine months of children’s sleep time is 10-12 hours a day. Adequate sleep is more conducive to the growth and development of the child’s body. If the sleep time is not normal, we should find out the reasons: on the one hand, it may be caused by environmental factors. On the other hand, it may be a lack of vitamin D or calcium, which increases the excitability of the cerebral cortex and causes sleep disorders in children. Nine months of pediatric sleep time is too long or too short, will affect the growth and development of the child, if abnormal to the hospital to identify the causes, make appropriate treatment.