Executive functions (EFs) are a set of cognitive control processes involved in the regulation of basic psychological functions such as attention, memory and emotion. Meta-analytic evidence supports the presence of impaired EFs in individuals with insomnia disorder, the most common sleep disorder affecting one third of the general population and associated with mental and physical illness. The effects of standard treatment for insomnia (i.e., cognitive behavior therapy for insomnia, CBT-I ) on EFs, however, are yet to be clear. In fact, only four studies investigated the impact of CBT-I on EFs with inconsistent results. The aim of this study is to investigate the effectiveness of CBT-I on EFs using a randomized active-controlled trial design. Thirty patients with a diagnosis of insomnia disorder will be randomly allocated either to the experimental or the control group. The experimental group will receive four weekly sessions of CBT-I in a face-to-face individual setting. Treatment will include the techniques of stimulus control, sleep compression, cognitive restructuring, cognitive control, sleep hygiene and relaxation. Participants in the control group will receive the same CBT-I techniques but in a self-help format (booklets plus weekly calls of a clinical psychologist). EFs will be measured at baseline, after treatment and after two months of follow up using the Task Switching paradigm which assesses the EFs of response inhibition and cognitive flexibility. Results will be analyzed through a 3x2 mixed design factorial ANOVA Time (baseline vs post-test vs follow up) x Group (Treatment vs Control) on the two indices of the Task Switching performance (Backward Inhibition and Switch Cost, measures of response inhibition and cognitive flexibility, respectively). This study will advance the knowledge on the effectiveness of CBT-I on daytime functioning of individuals with insomnia.
Several meta-analyses support the effectiveness of CBT-I in improving sleep of patients with insomnia (e.g. van Straten et al. 2017, Geiger Brown et al. 2015). Only recently, though, researchers stared to investigate the effects of CBT-I on daytime functioning, that is paradoxically, the reason why patients with insomnia seek clinical help (Riedel et al. 2000). Thus, CBT-I was shown to decrease comorbid psychiatric symptoms (e.g. Wu et al. 2016), negative mood (e.g. Ballesio et al. 2017) and fatigue (e.g. Vitiello et al. 2009). Nevertheless, few research was conducted on the effects of CBT-I on cognitive impairments, and specifically on EFs. de Bruin et al. (2015) found that group CBT-I improves EFs in an adolescent sample, while Altena et al. (2008) found that CBT-I improves the functioning of prefrontal cortex, an area of the brain associated with EFs. In this context, the implementation of the proposed study will advance the research investigating the effects of CBT-I on two specific core EFs, namely response inhibition and cognitive flexibility.