Downers are a group of drugs that all have similar sedating qualities. The word downer is an umbrella term that includes benzodiazapines, barbiturates, and alcohol. Downers are also sometimes referred to as tranquilizers, hypnotic sedatives, or depressants. Because of the widespread social use of alcohol, it is often considered its own class of drug.
The common denominator for downers is their effect on the neurotransmitter gamma-aminobutyric acid, or GABA. GABA is responsible for calming the central nervous system, slowing heart rate, breathing, and inducing sleep. Effectively, it works to counter the effects of the neurotransmitter norepinephrine, and the two work in conjunction to maintain proper heart rate, and alertness. Too much norepinephrine can lead to a number of anxiety disorders and can be responsible for ‘panic attacks’, and so downers are often prescribed to treat these conditions.
Narcotics and opiate based pain killers are sometimes lumped together with downers. While opiates do produce a sedating effect on the body, they do not directly effect the neurotransmitter GABA and are therefore a different class of drugs.