To Örebro University

Background: The Minimal Insomnia Symptom Scale (MISS) is a three-item screening instrument that has been found to be psychometrically sound and capable of screening for insomnia among adults and older people. This study aimed to test the measurement properties of the MISS together with an additional item focusing on daytime functioning among adolescents using the Rasch measurement model.

Methods: A cross-sectional design was used, and data from adolescents (age 13–17 years, n = 3022) were analyzed using the Rasch measurement model.

Results: The MISS had good measurement properties. When adding the item “daytime disturbance”, the measurement properties deteriorated. When replacing the original MISS item “not rested by sleep” with the item “daytime disturbance”, the measurement properties slightly improved. We label this new scale the MISS-Revised (MISS-R). The reliability was better for the MISS-R (0.55) compared to the MISS (0.50). The optimal cut-off was found to be > 6 points, both for the MISS and the MISS-R.

Conclusions: This study provides general support that both the MISS as well as the MISS-R have good fit to the Rasch model. At this stage, neither the MISS nor the MISS-R can be advocated over the other for use among adolescents, although the MISS-R had slightly better reliability than the MISS. Additional studies are needed to determine the clinically optimal cut-score for identification of insomnia.