complementary aspects of the same circadian cycle. The modifi­ cation of sleep parameters by hypnotic medication must necessarily have an impact upon daytime behaviour. The overall change in a patient's daytime behaviour following nocturnal administration of a benzodiazepine is of importance when considering the toler­ ability and safety of the drug in clinical use. Alterations to the integrity of daytime performance also have consequences for that patient's subsequent sleep and nocturnal behaviour. Thus this workshop was conceived as a platform for examining the inter­ relationship of sleep, benzodiazepine hypnotics and daytime performance from pharmacological, psychological, experimental and clinical standpoints. The fol­ lowing papers also highlight the complexity of the interaction between sleep, patient, drug and daytime performance and emphasize the need to approach problem areas with appropriate research strategies and experimental method­ ologies.