2.mi band sports games are synchronous, but sleep asynchronization is caused by wrong sleep settings. The solution is as follows: First, download a Xiaomi sports APP on Xiaomi's mobile phone, and then turn on its bracelet before going to bed. After the connection is successful, leave the bracelet on your wrist or use it as a pendant accessory.
3. The reason why 3.mi band 4 has no sleep data is that the sleep data needs to be synchronized. If your bracelet doesn't show the sleep time after synchronization, I suggest you unbind the bracelet first, and then rebind it to check whether Xiaomi Sport is the latest version.
4.mi band's daytime sleep can't be detected, because mi band's sleep recording period is valid from 19 to 8: 00 am. If he doesn't get up at night, he can continue recording in the morning. If he gets up in the morning and goes to bed, the mi band doesn't record sleep.