Overview: "Downers" is a name for depressant drugs, known medically as sedative-hypnotics. The group includes a range of chemicals that depress (or slow down) central nervous system functions. Two drug families have long dominated the depressant group: barbiturates and benzodiazepines, although a new group of non-benzodiazepines (which includes such drugs as Ambien® and Lunesta®) has emerged as one of the fastest-growing categories of prescription drugs in the world.

Street Names: Often based on the color of a tablet or capsule: yellowjackets (Nembutal®), reds (Seconal®), blue bombers (Amytal®), etc.

Appearance: Tablets and capsules.

Actions/Effects: Some downers target neurotransmitters that regulate anxiety, while others reduce activity throughout the central nervous system. Still, all trigger similar physical and emotional changes. Normal doses reduce anxiety or induce sleep, but tend to slow breathing and reduce blood pressure, reflexes, and body temperature. At higher doses (or when used with the most common CNS depressant, alcohol), downers can slow key body systems so much that they stop altogether.

Medical Uses: Depressants are prescribed to treat insomnia, manage anxiety, and reduce convulsive and neuromuscular disorders.

Risks/Side Effects: All depressants reduce cognitive and motor skills, although benzodiazepine tranquilizers (Xanax®, Valium®) tend to impair these functions less than other drugs in the class. Downers can also decrease judgment and increase reaction time. Because of the length of time necessary to break down some depressants in the body, subtle effects can continue for hours or days after use.

Abuse Potential: Moderate to high. Tolerance (the need to use increasing amounts to produce desired effects) is often so great that many manufacturers warn against using sleeping pills for more than a week or two, and suggest that tranquilizers be used only a month or so.

Duration: Varies, depending on the drug.

Trends: After an explosive increase in the 1970's, minor tranquilizer use has slowed in recent years. Use of barbiturates has fallen even more, and methaqualone (Quaalude®) has disappeared as a drug problem altogether, due to international controls on its production.

Demographics: Although depressant use has declined in recent surveys (which show prior-month use of tranquilizers by U.S. adults fell from 4,200,000 in 1985 to 1,817,000 by 2005), the U.S. introduction of Ambien in 1993 helped fuel a massive surge in the use of sleeping aids. To date, more than 12 billion doses of Ambien have been prescribed worldwide.