Insomnia is worldwide the most common sleep disorder among adolescents with estimates of a point prevalence ranging from 7.8%
up to 23.8%. Insomnia is defined as difficulty initiating and/or maintaining sleep, or non-restorative sleep, for at least
3 days per week, accompanied by significant daytime impairment, for at least 3 months, despite adequate opportunity to sleep.
It tends to persist over time with high chronicity. Insomnia has a bidirectional relationship with psychopathology, suggesting
that it can cause or exacerbate other mental disorders such as depression, anxiety, and even ADHD. Studies show that adolescents
with disturbed sleep report more depression and anxiety, inattention and conduct problems, drug and alcohol abuse, and impaired
academic performance. Furthermore, adolescents with sleep disturbances report worse perceived health, more sleepiness, energy
loss, and daytime fatigue. Cognitive Behavioral Therapy for Insomnia (CBTI) is the first choice for treatments of adults,
but CBTI has not been investigated in a randomized controlled trial in adolescents. Furthermore, adolescents are reluctant
to seek help for psychological problems, and availability of CBTI falls short of the demand. Internet therapy has been shown
to be feasible in adolescents, and therefore CBTI delivered through the Internet could fill the gap between demand and availability
of insomnia treatment.
In this dissertation a tailored CBTI protocol for adolescents called "Slim Slapen" (Sleeping Smart),
was investigated for efficacy of group- and Internet therapy compared to a waiting list condition, for sleep, psychopathology,
cognitive functioning, and cost-effectiveness.