paraldehyde (pârălˈdəhĪdˌ) [key], nervous system depressant similar to alcohol in its effects and used as a sedative. A colorless flammable liquid with a disagreeable odor, paraldehyde produces sleep for up to 12 hr. with little or no muscle, heart, or respiratory depression. It is often given to alcoholics having delirium tremens, to induce sleep, and is also used to calm psychiatric patients. Like alcohol and other depressants it is addictive (see drug addiction and drug abuse). Paraldehyde is also used in the manufacture of synthetic resins, as a preservative, and in preparing leather. It is produced by treating acetaldehyde with a small amount of sulfuric acid.