Go to Settings > Use your phone healthily, and click on.
Select I Use, and then click OK.
Not bad.
Click the available time to set the total time allowed to use the mobile phone every day.
Click Application Restrictions, select the application to be set, and set the time allowed to use the application.
Click Deactivation Time > Add Deactivation Time, and set the time period for disabling the mobile phone according to the prompts.