Molecular approaches towards the isolation of sleep-related genes

Behavioural genetics is one of the most enticing fields in modern biology. Owing to straightforward and semiautomated techniques that can be used to m easure locomotor activity, circadian rhythmicity is perhaps the best studie d behaviour in animals. Thus, during the past decade, five essential circad ian clock genes have been isolated in Drosophila, and homologous counterpar ts for all of these genes have also been found in mammals. As the sleep-wak e cycle is under the control of the circadian clock, these circadian master genes are expected to influence sleeping behaviour. However, different vig ilance states are regulated by additional mechanisms that also have a genet ic basis. In this article we discuss molecular approaches that may prove us eful in the search for sleep-related genes.