Forty-eight individuals with insomnia were asked to wear an actigraph and keep a sleep diary for 2 nights. On the following day, half were shown the discrepancy between the data recorded on the actigraph and their sleep diary via a behavioral experiment, whereas the other half were told of the discrepancy verbally. Participants were then asked to monitor their sleep for 2 further nights to index the effect of these interventions. Although both reduced sleep misperception, the behavioral experiment (effect size: 0.79 to 1.25) led to greater reduction in self-reported sleep impairment, insomnia symptoms, and sleep-related anxiety and distress compared with verbal feedback (effect size: −0.06 to 0.31). Further, the patients regarded the behavioral experiment as a more beneficial and acceptable intervention strategy than verbal feedback.