Sedatives are general depressants; they retard signals passing through the central nervous system. They also inhibit or slow down a number of functions and the action of a wide range of organs of the body, as well as general activity, or "behavioral output." Sedatives also decrease anxiety. At higher doses, sedatives are also hypnotics, that is, they induce sleep. The term "sedative-hypnotic" can be regarded as synonymous with "general depressant"; I'll simply use the term "sedative" to cover drugs that act as general depressants. Alcohol is the most widely used of all sedatives; it was discussed in Chapter 5. Barbiturates are another type of sedative; so is methaqualone. Others include chloral hydrate and the bromides—drugs that are hardly used at all today.

The principal function of the tranquilizers is treatment of neuroses and psychoses. The "minor" tranquilizers are used for "minor" mental illness, or neuroses; the "major" tranquilizers are used for "major" mental illnesses, or psychoses. "Minor" tranquilizers produce a reduction in the user's level of anxiety. The characteristics that presumably set tranquilizers apart from sedatives, and made them superior to sedatives as therapeutic igents, were that they were nonaddicting and produced no mental clouding or drowsiness in the user. Later experience with all of the "minor" tranquilizers has shown that they are, in fact, addicting, and do produce mental clouding. Actually, the differences between the "minor" tranquilizers and the sedatives are fewer and much less significant than the similarities. Major" tranquilizers suppress the symptoms of psychosis. They do not produce intoxication or a high, and are rarely used illegally for recreational purposes.