Table 1 Inclusion and exclusion criteria

Inclusion criteria

 16 to 22 years old

 Living in UK, Spain, Germany, Belgium

 Fluent in at least one of English, Spanish, German, Dutch (Flemish)

 Able to provide informed consent or parents willing to provide consent if under 18 years of age in Germany and Belgium

 Regular access to Android or iOS smartphone

Exclusion criteria

 Current or Lifetime diagnosis of Major depressive Disorder (DSM-IV criteria, LIDAS self-report).

 Current use of antidepressant drugs or psychological interventions

 History of psychosis, bipolar disorder, substance dependence or other severe psychiatric disorder or current suicidality