Children have smartphones already is a very common phenomenon, they all look at mobile phones, do what they like, including mobile phone game chat with friends is the most common things they do. Even when they're asleep they want to see the phone. They lay in bed at night watching mobile phone, this is not only damaging their vision, also can rest have a big impact to them, I feel that the school was a nap should also open
cell phone signal blocker jammer to ban children at rest to see the behavior of the mobile phone.