Cognitive “insomnia” processes in delayed sleep–wake phase disorder: do they exist and are they responsive to chronobiological treatment?

Objective: To systematically investigate whether cognitive "insomnia" processes are implicated in adolescent Delayed Sleep-Wake Phase Disorder (DSWPD) and to examine whether these processes are responsive to chronobiological treatment. Method: Sixty-three adolescents (M = 15.8 ± 2.2 years, 63.5% f) diagnosed with DSWPD and 40 good sleeping adolescents (M = 15.9 ± 2.4 years, 75% f) completed baseline measures of sleep, daytime functioning and cognitive "insomnia" processes (i.e., repetitive negative thinking, physiological hyperarousal, distress, sleep-related attention and monitoring, sleep misperception). Sixty DSWPD adolescents (M = 15.9 ± 2.2 y, 63% f) entered a treatment trial and received 3 weeks of light therapy. Sleep, daytime functioning, and insomnia were measured again post-treatment and at 3-month follow-up. Results: Adolescents with DSWPD had significantly later sleep timing (d = 0.99 -1.50), longer sleep latency (d = 1.14), and shorter total sleep time (d = 0.85) on school nights, compared with the good sleeping adolescents. There was evidence of cognitive "insomnia" symptoms, with the DSWPD group reporting more repetitive negative thinking (d = 0.70 -1.02), trait hyperarousal (d = 0.55), distress (d = 2.19), sleep associated monitoring (d = 0.76), and sleep onset misperception (d = 1.29). Across treatment and follow-up, adolescents with DSWPD reported advanced sleep timing (d = 0.54 -0.62), reduced sleep latency (d = 0.53), increased total sleep time (d = 0.49), and improved daytime functioning (d = 0.46 -1.00). Repetitive negative thinking (d = 0.64 -0.96), physiological arousal (d = 0.69), distress (d = 0.87), and sleep onset misperception (d = 0.37) also showed improvement. Conclusions: Cognitive "insomnia" processes may be implicated in the development and maintenance of DSWPD in adolescents. Many of these processes are amendable to chronobiological treatment; however, residual symptoms may place adolescents at risk of poor treatment outcome or relapse.