Figure 1

Distribution of morningness-eveningness scores. The percentiles of Horne-Östberg morningness-eveningness scores are plotted for 5 groups: a) absolutely certain DSPD 1, b) fairly certain DSPD 2, b) questionable DSPD 3, d) unlikely or very doubtful DSPD 4–5, and e) DSPD-C matched controls. Low HO scores indicate eveningness and high scores indicate greater morningness. In this study, the best criterion separating DSPD and DSPD-C was a score of 41.