By analysing literature that has been published since 2011 when smartphones first became widespread, the range of studies showed that 10-30% of children and young people used their smartphones in a dysfunctional way, which means an average of 23% were showing problematic smartphone usage (PSU).

PSU was defined as any behaviour linked to smartphones that has the features of an addiction, such as feeling panicky or upset when the phone is unavailable, finding it difficult to control the amount of time spent on the phone and using the phone to the detriment of other enjoyable activities.

The study is the first to investigate the prevalence of PSU in children and young people at this scale, summarising findings from 41 studies that have researched a total of 41,871 teenagers and young people. The 41 studies included 30 from Asia, nine from Europe and two America. 55% of the participants were female, and young women in the 17 to 19-year-old age group were most likely to have PSU.

The researchers also investigated the links of this type of smartphone usage and mental health and found a consistent association between PSU and poor measures of mental health in terms of depressed mood, anxiety, stress, poor sleep quality and educational attainment.