阅读材料，根据材料内容从每小题所给的A、B、C、D四个选项中，选出一个最佳选项。
Sleepwalking（梦游）is when your child gets out of bed and walks around as if he's awake, but he's actually asleep. Sleepwalking doesn't hurt your child, and it usually disappears when the kid grows up.
Sleepwalking happens during deep sleep. Your child might get out of bed and walk around as if he's awake, but he won'trespondnormally to you or anything around him. This may make you upset. But try not to worry—your child is OK.
In fact, sleepwalking is quite common. 7% to 15% of children sleepwalk, and it doesn't usually mean that there's anything wrong with them. Children aged 4 to 12 are more likely to sleepwalk. Both boys and girls sleepwalk.
Sleepwalking often happens in the first few hours of the night. When it happens, your child's mind is asleep. However, his body is awake at the same time.
Sleepwalking usually has something to do with age and development. However, some things can increase your child's sleepwalking. For example:
•Bad habits that cause poor sleep
•Fever or some other illnesses
•A family history of sleepwalking
• Medical conditions that cause poor sleep
If your child is sleepwalking at least once every night, it's best to see a doctor. Also see a doctor if your child's sleepwalking is influencing the sleep of other family members, or if you 're worried your child might hurt himself while sleepwalking.