Parasomnias are a heterogeneous group of undesirable, but not always pathological, manifestations that accompany sleep. They consist in abnormal behaviors due to the inappropriate activation of cognitive processes or physiological systems such as the motor and/or autonomic nervous systems. In some cases, they can result in sleep disruption and injuries, with adverse health or psychosocial consequences for patients, bed-partners or both. According to the International Classification of Sleep Disorders, parasomnias are distinguished on the basis of the stage of sleep in which they appear: (1) parasomnias arising from NREM (non-rapid eye movement) sleep, which include arousal disorders (confusional arousal, sleep terror, sleepwalking) and sleep-related eating disorders; (2) parasomnias associated with REM (rapid eye movement) sleep; and (3) “other parasomnias” occurring in any sleep stage (eg, sleep enuresis, exploding head syndrome). This chapter describes the NREM parasomnias and the “other parasomnias,” underlining the more recent and significant advances that have provided a better understanding of their clinical features and pathophysiology.