Inclusion Criteria:  Functioning deterioration of the child (age 12-16) due to online activity in the past 6 months in at least one of the following domains: school, social relationships, participation in family activities, sleeping patterns, and mood (according to parents' self-report). The child owns a mobile phone.  Exclusion Criteria:  A psychiatric diagnosis of the child A significant personal crisis in the previous 12 months (e.g., divorce, loss of a significant person) A parental control application is installed on their children's mobile phones.