Sedatives are central nervous system (CNS) depressants, a category of drugs that slow normal brain function. There are various kinds of CNS depressants, most of which act on the brain by affecting the neurotransmitter gamma-aminobutyric acid (GABA). Neurotransmitters are brain chemicals that conduct communication between brain cells. GABA works by decreasing brain activity. Although the different types of CNS depressants each work in their own way, ultimately it is through their ability to increase GABA activity that they produce a relaxing effect that is beneficial to those suffering from anxiety or sleep disorders.
Among the medications that are commonly prescribed for these purposes are the following:
Barbiturates, such as mephobarbital (Mebaral) and pentobarbital sodium (Nembutal), which are helpful in treating anxiety, tension, and sleep disorders.
Benzodiazepines, such as diazepam (Valium), chlordiazepoxide HCl (Librium), and alprazolam (Xanax), which can be prescribed to treat anxiety, acute stress reactions, and panic attacks; the more relaxing benzodiazepines, such as triazolam (Halcion) and estazolam (ProSom) can be prescribed for short-term treatment of sleep disorders.
In higher doses, some CNS depressants can be used as general anesthetics.
Despite their many beneficial effects, barbiturates and benzodiazepines have the potential for abuse and should be used only as prescribed. During the first few days after taking a prescribed CNS depressant, a person usually feels drowsy and uncoordinated, however this will diminish. If one uses these drugs long term, the body will develop tolerance, and larger doses will be required to achieve the same initial effects. In addition, continued use can lead to physical dependence and—when use is lessened or stopped—withdrawal. Because all CNS depressants work by slowing the brain's activity, when an individual stops taking them, the brain's workings can rebound and race out of control, possibly resulting in seizures and other harmful consequences. Although withdrawal from benzodiazepines can be a difficult experience, it is rarely life threatening, whereas withdrawal from prolonged use of other CNS depressants can have life-threatening complications. Therefore, someone who is thinking about discontinuing CNS depressant therapy or who is suffering withdrawal from a CNS depressant should speak with a physician or seek medical treatment.
At high doses or when they are abused, many of these drugs can even cause unconsciousness and death.
Activity of the central nervous system becomes slowed down. Small doses relieve tension; large doses produce staggering, blurred vision, impaired perception of time and space, slowed reflexes and breathing, reduced sensitivity to pain, impaired thinking, and slurred speech. Overdoses cause unconsciousness, coma, and death. Accidental overdoses occur when children swallow pills or when adults with increased tolerance are unsure of how many to take.
CNS depressants should be used with other medications only under a physician's supervision. Typically, they should not be combined with any other medication or substance that causes CNS depression, including prescription pain medicines, some over-the-counter cold and allergy medications, or alcohol. Using CNS depressants with these other substances—particularly alcohol—can slow breathing, or slow both the heart and respiration, possibly resulting in death.
Health risks include anemia, depression, impairment of liver function, and chronic intoxication (headache, impaired vision, slurred speech). Babies of chronic users may have difficulty in breathing and feeding, disturbed sleep patterns, sweating, irritability and fever.
Very significant levels of physiological dependence marked by both tolerance and withdrawal can develop in response to the sedatives, hypnotics, and anxiolytics. The timing and severity of withdrawal issues will differ depending on the specific substance and its pharmacokinetics and pharmacodynamics.
Sedatives. Last reviewed 10/10/2006
- Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Revised
- National Institute on Drug Abuse