Depressants, or "downers," are drugs that slow the central nervous system. One type of depressant is a barbiturate, commonly prescribed for anxiety or insomnia. Barbiturates can be addictive, and when mixed with other drugs or alcohol the effects can be fatal. Types of barbiturates include phenobarbital (Nembutal), mephobarbital (Mebaral), and secobarbital (Seconal). Slang terms used for barbiturates includes "barbs," "reds," red birds," "phennies," "tooies," "yellows," and "yellow jackets."