We tested the hypothesis that patients with extreme sleep state misperception display higher levels of psychopathology and reduced quantitative estimation abilities compared to other patients with insomnia. Secondary aims included the evaluation of group differences in subjective self-reported quality of life and sleep quality and objective sleep parameters. In this cross-sectional, observational study, 249 patients with insomnia underwent a video-polysomnography with a subsequent morning interview to assess self-reported sleep estimates and filled in a large battery of questionnaires. Patients were classified into High Misperception (HM) and Moderate Misperception (MM) groups, according to the complement of the ratio between self-reported total sleep time and objective total sleep time (Misperception Index). No significant differences emerged in any of the psychopathological measures considered between the HM and the MM group. Similarly, no effect was observed in quantitative estimation abilities. HM patients displayed a significantly increased number of awakenings per hour of sleep and a reduced dream recall rate. Their overall sleep quality and quality of life was significantly impaired. Future research on sleep misperception should focus on factors other than the level of psychopathology and estimation abilities, in particular sleep microstructure and quantitative EEG studies in both REM and NREM sleep.