Tests of performance and alertness in normal older subjects undergoing sleep loss reveal loss of performance and alertness similar to that seen in younger individuals. Recovery of performance ability occurs with one night of normal sleep, even following periods of sleep loss up to 64 hours in length. Older individuals, including older individuals with primary insomnia, may tolerate sleep loss with less decrease in ability compared with their baseline than young adults and may recover function more quickly than young adults. While it has been frequently shown that older individuals perform more poorly than young adults on a broad range of tasks, these findings do not hold well for periods of nocturnal performance or performance during sleep loss. It is possible that these findings may be accounted for to some extent by the decrease in amplitude of the circadian body temperature curve in older individuals. It is unfortunate that Reynolds et al did not attempt to collect performance data in their depressed and demented patients to determine if the differential effects on mood and EEG would also be reflected in psychomotor performance.