It has been proposed that there are two distinct insomnia phenotypes that could be differentiated by a cut-off of 6 hours in objectively measured (PSG or actigraph) sleep duration. The phenotype with short sleep duration, characterized by physiological hyperarousal, was found to be associated with activated HPA axis and higher cardiovascular and metabolic risks and comorbidity; the phenotype with longer sleep duration, characterized by cognitive-emotional and cortical arousal, was found to be associated with sleep misperception and a psychological profile with more emotional disturbances. A recent study further indicated that the first phenotype showed less response to cognitive behavioral therapy for insomnia. Since sleep-related psychological and behavioral factors are considered to be the main etiological factors for chronic insomnia, the present study aims to explore the profiles of these factors in the two phenotypes of insomnia
