Amphetamine use disorders are a category of substance use disorders and describes the dependence and/or addiction to amphetamines. Amphetamines are a class of psychoactive drugs that increase energy, helps the user to resist sleep and remain alert for extended periods of time, and can cause weight loss. Medically, they have been used for the treatment of narcolepsy, obesity, hay fever, orthostatic hypotension, attentional disorders, epilepsy, Parkinson's disease, alcoholism, and migraine headaches. However, the "reinforcing" or pleasurable effects of amphetamine drugs were quickly discovered and the misuse of medicinal amphetamines has been known for decades. There are many types of amphetamines currently on the market medically, and others, such as methamphetamine are cooked up in illegal "meth labs."