The results from six separate evaluations of flurazepam 30 mg in the sleep laboratory were combined to determine the effectiveness of the drug in inducing and maintaining sleep and its effects on sleep stages in a large sample of insomniac subjects. The combined studies provide a model from which a detailed profile of the effects of a hypnotic drug over short-, intermediate-, and long-term conditions can be thoroughly evaluated. Although sleep was significantly improved on the first night of flurazepam administration, peak effectiveness of the drug did not result until the second and third consecutive drug nights. Flurazepam continued to be effective in inducing and maintaining sleep with intermediate-and long-term drug use with only a slight loss of effectiveness with long-term use. Sleep was also significantly improved on the first and second nights of drug withdrawal. Carryover effectiveness of active metabolites of flurazepam from one drug night to the next drug night and to withdrawl nights is discussed. The clinical implications are discussed with regard to the time of peak effectiveness of the drug, dosage recommendations and schedule, minimizing possible effects of the drug on daytime performance, and the rationale and method for using drug holidays in the treatment regimen. With this comprehensive profile of the drug's actions, the physician is able to more rationally and effectively utilize the drug in treating the insomniac patient. With short-term administration, flurazepam produced a slight decrease in rapid eye movement (REM) sleep and an increase in REM latency. These effects were much more pronounced with intermediate-term drug administration, again possibly due to the accumulation of active metabolites. After withdrawal there was no rebound in REM sleep. Stages 3 and 4 sleep decreased progressively through short and intermediate drug administration. With initial withdrawal, there was a slight recovery in both sleep stages.