ISES: a new bidimensional scale for assessing self efficacy in insomnia

The construct of Self Efficacy is very influential in health and clinical psychology (e.g. 1) and is gaining relevance in the understanding of insomnia (2). Some studies emphasized the importance of self efficacy in predicting the treatment response to Cognitive Behavioral Therapy for insomnia (3). The present study is aimed to introduce a bidimensional self-efficacy scale evaluating: (a) the perceived ability to initiate and to maintain sleep; (b) the perceived ability to stand the diurnal consequences of a poor sleep. The Insomnia Self Efficacy Scale (ISES) is composed of 10 items requesting to assess different abilities on a 5 point scale. 731 patients of GP (mean age 42.9 SD 16.4; female 73.3%) completed the ISES and a screening questionnaire for sleep disorders (QDS, 4). The bifactorial structure of the ISES were tested through a confirmative factor analysis and its factorial invariance was evaluated through a multigroup analysis considering 140 (19.2%) patients without sleep complaints, 177 (24.2%) with DSM-IV insomnia, and 414 (56.6%) with subcriterial DIMS or other sleep problems. The data show adequate fit to the bidimensional model (v2 = 311.85, P < 0.001; NNFI = 0.94; CFI = 0.95; RMSEA = 0.11). The ISES bifactorial structure is stable in the patients with insomnia and in those without sleep problems (v2= 204.58; NNFI = 0.94; CFI = 0.95; RMSEA = 0.10) however in the latter they are highly correlated while in the former they are independent. ANOVAs show that for both subscales in the insomnia group the self efficacy scores are lower compared to both other groups (F2.271 = 94.5; F2.270 = 12). Further studies will evaluate the validity of the ISES in predicting compliance to treatments for insomnia and in assessing their results.