Background and purpose: Physiological, cognitive, and behavioral factors are considered as the underlying causes of insomnia. Accordingly, the present study aimed to investigate the roles of some cognitive and emotional factors in predicting insomnia disorder.

Materials and methods: To conduct this cross-sectional study, two groups were randomly selected. The first group comprised of 100 patients suffering from insomnia attending Sleep Disorders Center in Kermanshah Farabi Hospital, Iran 2015. The second group consisted of 100 office workers in Kermanshah University of Medical Sciences who were normal sleepers. For data collection six questionnaires were utilized, including sleep quality scale, difficulties in emotion regulation scale, meta-cognitive beliefs, repetitive negative thinking, experiential avoidance questionnaire, and dysfunctional beliefs and attitudes about sleep scale.

Results: This study showed significant differences between the two groups in all predictor variables (sleep quality, difficulties in emotion regulation, meta-cognitive beliefs, repetitive negative thinking, experiential avoidance, and dysfunctional beliefs and attitudes about sleep) (P<0.01) and that all these variables could predict insomnia. The results also indicated that dysfunctional beliefs and attitudes about sleep carried the highest weight for predicting insomnia (0.71) followed by repetitive negative thinking (0.38), while meta-cognitive beliefs had the lowest weight (-0.05). Finally, stepwise discriminant analysis confirmed the roles of two independent variables for entering into the discriminant equation.

Conclusion: The present study confirmed the roles of cognitive and emotional variables in the occurrence of insomnia so, they should be considered in treating insomnia.