Hypersexuality is known as nymphomania when in females and satyriasis when in males. It is a stronger than usual urge to have sexual intercourse. Masturbation causes euphoria (extreme pleasure). It is caused by some stimulant drugs, such as amphetamine. It is also caused by some mental disorders: bipolar disorder, schizoaffective disorder, borderline personality disorder, histrionic personality disorder. Some cases are of unknown cause. Some psychologists think it can be caused by a hormone imbalance. Others believe it is caused by early exposure to pornography and sex.