Nightmares are long, detailed dreams that usually happen during REM sleep. They involve intense negative emotions that lead to waking up, often as a person tries to avoid threats to survival, safety, or physical well-being, and typically results in rapid alertness and orientation upon awakening. Nightmares can also leave lingering negative feelings, cause significant distress, emotional dysregulation, and impair social, occupational, or other areas of functioning.
People with nightmare disorder show altered resting-state brain activity compared to healthy volunteers. Fifteen nightmare disorder patients and 15 healthy controls completed questionnaires and resting-state fMRI scans. Patients scored higher on measures of physical effect and horrible stimulation from nightmares. They had higher regional homogeneity (a measure of local brain connectivity) in the left anterior cingulate cortex and right inferior parietal lobule, and lower regional homogeneity in the left superior and inferior frontal gyri and bilateral middle occipital gyri.