Mental health problems in adolescents with delayed sleep phase: results from a large population‐based study in <scp>N</scp>orway

The aim of the current study was to compare mental health problems, resilience and family characteristics in adolescents with and without delayed sleep phase (DSP) in a population-based sample. Data were taken from the youth@hordaland-survey, a large population-based study in Hordaland County in Norway conducted in 2012. In all, 9338 adolescents aged 16-19 years (53.5% girls) provided self-reported data on a wide range of instruments assessing mental health symptoms, including depression, anxiety, obsessive-compulsive behaviours, attention deficit hyperactive disorder (ADHD) symptoms, perfectionism, resilience and sleep. Measures of socioeconomic status were also included. Three hundred and six adolescents (prevalence 3.3%) were classified as having DSP [according to the International Classification of Sleep Disorders-2 (ICSD-2)] criteria. Adolescents with DSP reported higher levels of depression, anxiety and ADHD symptoms. Adolescents with DSP also exhibited significantly lower levels of resilience. The Cohen's d effect sizes ranged from small [obsessive-compulsive disorder (OCD): d = 0.15] to moderate (inattention: d = 0.71). In the fully adjusted model, the significant predictors of DSP included inattention [odds ratio (OR): 2.11], lack of personal structure (OR: 2.07), low (OR: 1.85) and high (OR: 1.91) paternal education, parents not living together (OR: 1.81), hyperactivity/inattention (OR: 1.71) and poorer family economy (OR: 1.59). In conclusion, the high symptom load across a range of mental health measures suggests that a broad and thorough clinical approach is warranted when adolescents present with DSP.