Objective: To assess the effectiveness data of zaleplon. Data Sources: Primary and review articles were identified by MEDLINE (1985 to August 2000) and via secondary sources. Study Selection and Data Extraction: All of the articles identified from the data sources were evaluated, and all information deemed relevant was included in this review. Data Synthesis: Eight studies were identified. Two trials in a nonelderly population investigated the effectiveness of zaleplon and the incidence of withdrawal symptoms. Zaleplon's only significant effect on insomnia was to reduce sleep latency by six to 16 minutes. The tools used in the trials showed that stopping zaleplon after 14-28 days of therapy did not cause significant rebound events. Two recent studies that investigated the use of zaleplon in the elderly produced similar results, although one study showed that stopping zaleplon causes significant rebound events. Three studies determined whether zaleplon caused any hangover effects and concluded that there is a low potential for these effects in a nonelderly population. In healthy nonelderly volunteers, standard doses of zaleplon had no residual effects when taken as little as two hours before the subjects arose. One small-scale study indicated that the abuse potential of zaleplon is similar to that of benzodiazepines. Conclusions: Although zaleplon significantly reduces sleep latency, the effect does not appear to be highly clinically significant. Zaleplon's short half-life does appear to reduce the risk of hangover effects. Until further data become available, zaleplon should be considered to have the same abuse potential as benzodiazepines.