This study looked at sleep timing and mental health in a large group of young people in Norway. It drew on the youth@hordaland survey from 2012, which included 9,338 adolescents aged 16 to 19 years, just over half of them girls (53.5%). Of these, 306 were classed as having a delayed sleep phase, meaning their natural sleep timing ran late. That worked out to about 3 in 100 teens (3.3%).
Teens with a delayed sleep phase reported more depression, anxiety and ADHD symptoms, covering both inattention and hyperactivity or impulsivity, and they reported lower resilience than their peers. The gaps between the two groups ranged from small to moderate in size. The largest was for inattention (d = 0.71), followed by depression (d = 0.53), hyperactivity or impulsivity (d = 0.47) and anxiety (d = 0.29). The smallest gap was for obsessive-compulsive symptoms (d = 0.15).
When many factors were weighed together, inattention still stood out. Teens high in inattention were about twice as likely to have a delayed sleep phase (odds ratio 2.11). Lack of personal structure, family money worries and parents not living together also stayed linked to it.
The study measured everyone at one point in time, so it cannot show what caused what. Sleep timing was based on self-report, not a clinical check.
Source: Sivertsen B, Harvey A, Pallesen S, et al.. Mental health problems in adolescents with delayed sleep phase: results from a large population‐based study in N orway. Journal of Sleep Research (2014). doi:10.1111/jsr.12254