Hyperarousal and failure to inhibit wakefulness in primary insomnia: 'Birds of a feather'?

Primary insomnia ( PI) is one of the most prevalent sleep disorders. For this reason, over the last decades, several comprehensive and etiological theories have been proposed. In this paper we review some of the main theoretical models of insomnia and discuss the two most studied processes for comprehension of insomnia: the hyperarousal and the failure to inhibit wakefulness or psychobiological inhibition hypotheses. Some clinical implications of the models are described. In the end, we propose that the two processes are complementary and both are relevant to the understanding of clinical insomnia. [ABSTRACT FROM AUTHOR]