Arousal parasomnias occur mainly during non-rapid eye movement (NREM) sleep. This group consists of confusional arousals, sleepwalking and sleep terrors. Sleepwalking and sleep terrors can be triggered by stress, sleep deprivation, alcohol ingestion, and almost all sedative medications. This group of parasomnias is composed of three disorders occurring essentially during rapid eye movement (REM) sleep. Sleep paralysis is one of the main symptoms associated with narcolepsy, but it can also occur individually. REM sleep behavior disorder is characterized by a loss of generalized skeletal muscle REM-related atonia and the presence of physical dreamenactment. Polysomnographic recordings of individuals with RBD showed a reduction of the tonic phenomena of REM sleep and the activation of the phasic phenomena. Parasomnias are frequent in the general population; more than 30% of individuals experiences at least one type of parasomnia. At the genetic level, there is growing evidence that many parasomnias have a genetic component.