Variability of response to hypnotics: sleep studies in man.

Effect of diazepam on sleep in man was investigated in a series of placebo controlled studies and the data on various measures from two groups (young adults and middle age) were retrospectively analysed. Variability of the measures between the two groups with placebo was not different, but the variability of their response to the drug was different, and that of the middle aged group was high. In the young adults there were drug effects, but in the middle aged group no drug effects could be established. The studies suggest that variability of data must be taken into consideration when it is used to indicate the most appropriate dose range. If the variability of response is low the data may indicate the likely effect of the drug on each individual. On the other hand if the variability is high then data obtained from analysis of the group may have limited relevance, and suggest doses which are too high for the majority of the individuals within that group.