Hypnotic drugs, also called sedatives, cause sleep that resembles natural sleep. Ideally, these
drugs should induce or improve sleep without profound depression, and the effects should disappear upon awakening. The use of hypnotics has occurred throughout history, though some traditional preparations must have been effective because of the power of suggestion rather than because of demonstrable pharmacological effect. One of the earliest hypnotics was laudanum, a solution, usually alcoholic, containing opium. Alcohol itself has regularly been used as a hypnotic.
Barbiturates, discovered in 1903, were the most widely used
Hypnotic drugs until the 1970s; they are still used for some patients. This group of drugs acts by depressing the whole central nervous system. As the drug dose increases, the response goes from sedation to sleep, surgical anesthesia, coma, and ultimately fatal depression of breathing rate and blood pressure.
Barbiturates with an intermediate duration of action, such as secobarbital (Seconal) are used to treat insomnia. There are a number of side effects and problems associated with using barbiturates to induce sleep. Hangover, caused by a mild continued drug action after awakening, is common when
insomnia is treated with barbiturates. Patients
develop a
tolerance for the drug, which leads to decreased effectiveness, within a few days of repetitive use. This tolerance does not, however, prevent overdoses, which can cause death. In addition, dependence and addiction develop with continued use. If barbiturate use is stopped, withdrawal symptoms can develop, ranging from irritability and depression to convulsions. Barbiturates are a primary drug of
abuse (see drug abuse).
The most widely used hypnotic drugs for anxiety and insomnia are the benzodiazepines, also used as muscle relaxants and to treat epilepsy. These drugs depress a limited part of the central nervous system, including the part that controls sleep, unlike the barbiturates, so are much safer. Members of this group have varying periods of effectiveness: triazolam (Halcyon) works for 1Ð3 hours, temazepam (Restoral) for 5Ð6 hours, and flurazepam (Dalmane) and diazepam (Valium) for more than 24 hours. The shorter-acting drugs cause less of a hangover than barbiturates when used for the treatment of insomnia. Benzodiazepines can be taken for up to several weeks with little tolerance build-up and no difficulty stopping medication. However, after several months tolerance increases and withdrawal symptoms, including increased anxiety, can occur. Intentional abuse of prescription benzodiazepines is relatively rare. Zolpidem, a hypnotic drug with similar properties, was approved by the U.S. Food and Drug Administration in 1993.
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