Comparative investigation of the psychophysiologic and idiopathic insomnia disorder phenotypes: psychologic characteristics, patients' perspectives, and implications for clinical management.
Espie CA., Barrie LM., Forgan GS.
STUDY OBJECTIVES: Insomnia is a common disorder, yet its proposed behavioral phenotypes are seldom differentiated. Two consecutive studies were designed to investigate psychologic characteristics and treatment preferences of people with idiopathic insomnia (IdI) relative to psychophysiologic insomnia (PI). DESIGN: Cross-sectional, two-group comparison studies. SETTING: Specialized sleep research center. PARTICIPANTS: 40 participants (29 female, mean age 46 yr) participated in study 1. An additional cohort of 61 adults (48 female, mean age 37 yr) participated in study 2. In total, samples comprised 51 participants with PI and 50 with IdI. All participants met diagnostic criteria for their respective insomnia phenotype. INTERVENTIONS: N/A MEASUREMENTS AND RESULTS: Study 1 investigated sensitivity to arousal conditioning and sleep effort using self-report measures. Consistent with a model of conditioned arousal, participants with PI exhibited greater behavioral inhibition, i.e., sensitivity to threat and higher levels of sleep preoccupation. Study 2 investigated illness perceptions and cognitions and coping styles using self-report scales, and explored treatment acceptability based on the evaluation of 3 therapeutic scenarios. Results lend support to the hypothesis that IdI is considered somewhat more permanent than PI. Behavioral intervention was preferred to pharmacotherapy by both groups, and an acceptance treatment was considered more favorably by IdI study participants than by those with PI. CONCLUSIONS: Many similarities between IdI and PI were observed across psychologic measures, and both groups exhibited a preference for behavioral treatment. However, their distinctive characteristics appear to suggest that an acceptance-based therapy may also be appropriate for some people with IdI.