Sleep impairments including insomnia is a widespread problem affecting a large quantity of the population. Insomnia patients tend to worry about their sleep and having dysfunctional beliefs about sleep deficit consequences. The main purpose of this study was to examine if differences in results between two treatment methods could be attributed to effects of exposure. The hypotheses in the study were: 1a) Patients who participate in sleep restriction will have a greater reduction of sleep-related worry. 1b) There is a correlation between high compliance to the treatment methods and reduced sleep-related worry. 2) A greater exposure induces lower compliance to the treatment methods. 3a) There is a correlation between reduction of sleep-related worry and reduction of insomnia symptoms. Data consisted of 185 participants who was randomised into the CBT-treatments for insomnia sleep compression (n=93) or sleep restriction (n=92). A hypothesis was that sleep restriction implicate more exposure than sleep compression. Worry had decreased among participants after five weeks of treatment but no significant differences occurred between the groups. A significant correlation occurred between reduction of insomnia symptoms and reduction of worries regarding sleep deficit. Conclusions is that the already established correlation between worry and insomnia is confirmed. This study failed to confirm that exposure leads to reduced worry. Further research is advised to determine how exposure can be used for insomnia patients to enable more efficient treatment methods.