Background: Dysfunctional thinking has been seen as one of the major factors in the maintenance of insomnia; however, there is no literature to elaborate on the differences in thought processes in different insomnia subtypes. The aim of the present study was to assess if we could differentiate psychophysiological insomnia from co-morbid insomnia by noting specific pre-sleep issues relating to dysfunctional thought and behavior. Methods: Dysfunctional thought was noted for insomnia patients seen in Comprehensive Sleep Disorders Clinic at AIIMS, using a structured telephonic interview questionnaire. Later they were divided into two groups - patients with psychophysiological insomnia and patients with co-morbid insomnia. Responses were then analyzed using Fisher Exact test in STATA 11.0. Results: There was no significant difference found between the two groups, for most of the dysfunctional statements given in the questionnaire. However, a significant difference was found in response for one of the statements concerned with the effect on next day's behavior of the patient as a result of dysfunctional thinking. Conclusion: In this preliminary research, we found that patients with psychophysiological and co-morbid insomnia are similar in thoughts and behavior that are attributed to the maintenance of insomnia. However, the only difference noted was that patients with comorbid insomnia had significantly greater ‘worry about next day's functioning’ as a result of poor sleep and hence, affecting their behavior for the next day with regard to social and occupational functioning.