premise: Levoamphetamine is exclusively a sedative.
hypothesis: Amphetamine . Amphetamine properly refers to a specific chemical , the racemic free base , which is equal parts of the two enantiomers , levoamphetamine and dextroamphetamine , in their pure amine forms . Levoamphetamine , also known as levamfetamine ( INN ) , ( R ) - amphetamine , - amphetamine , and L-amphetamine , is a central nervous system ( CNS ) stimulant known to increase wakefulness and concentration in association with decreased appetite and fatigue .