RESUMO
The world-wide prevalence of insomnia disorder reaches up to 10% of the adult population. Women are more often afflicted than men, and insomnia disorder is a risk factor for somatic and mental illness, especially depression and anxiety disorders. Persistent hyperarousals at the cognitive, emotional, cortical and/or physiological levels are central to most theories regarding the pathophysiology of insomnia. Of the defining features of insomnia disorder, the discrepancy between minor objective polysomnographic alterations of sleep continuity and substantive subjective impairment in insomnia disorder remains enigmatic. Microstructural alterations, especially in rapid eye movement sleep ("rapid eye movement sleep instability"), might explain this mismatch between subjective and objective findings. As rapid eye movement sleep represents the most highly aroused brain state during sleep, it might be particularly prone to fragmentation in individuals with persistent hyperarousal. In consequence, mentation during rapid eye movement sleep may be toned more as conscious-like wake experience, reflecting pre-sleep concerns. It is suggested that this instability of rapid eye movement sleep is involved in the mismatch between subjective and objective measures of sleep in insomnia disorder. Furthermore, as rapid eye movement sleep has been linked in previous works to emotional processing, rapid eye movement sleep instability could play a central role in the close association between insomnia and depressive and anxiety disorders.
RESUMO
INTRODUCTION: Cognitive behavioral therapy for insomnia (CBT-I) is the current first-line treatment for insomnia. However, rates of nonresponse and nonremission are high and effects on quality of life are only small to moderate, indicating a need for novel treatment developments. We propose that Acceptance and Commitment Therapy (ACT) addresses core pathophysiological pathways of insomnia. ACT therefore has the potential to improve treatment efficacy when combined with bedtime restriction, the most effective component of CBT-I. The aim of this study was to compare the efficacy of ACT for insomnia combined with bedtime restriction (ACT-I) and CBT-I in improving insomnia severity and sleep-related quality of life. METHODS: Sixty-three patients with insomnia disorder (mean age 52 years, 65% female, 35% male) were randomly assigned to receive either ACT-I or CBT-I in a group format. The primary outcomes were insomnia severity (Insomnia Severity Index) and sleep-related quality of life (Glasgow Sleep Impact Index). Outcomes were assessed before randomization (T0), directly after treatment (T1), and at 6-month follow-up (T2). RESULTS: The results indicated significant, large pre-to-post improvements in both groups, for both primary and secondary outcomes. Improvements were maintained at the 6-month follow-up. However, there was no significant group by time interactions in linear mixed models, indicating an absence of differential efficacy. On a subjective treatment satisfaction scale, patients in the ACT-I group indicated significantly greater satisfaction with their improvement of several aspects of health including their energy level and work productivity. CONCLUSIONS: The results suggest that ACT-I is feasible and effective, but not more effective than CBT-I for the improvement of insomnia severity and sleep-related quality of life. Future studies are needed to assess whether ACT-I is noninferior to CBT-I and to shed light on mechanisms of change in both treatments.