IN JAPAN, patients rarely say "yes" if a physician asks, "Have you had any difficulty sleeping in the past month?" In the United States, about 30% of the population describes restless nights, while in Brazil, the country with the highest selfreported prevalence, about 40% of the population does so.
While cultures vary in their perception and reporting of sleep problems, human physiology presumably is similar worldwide. Respecting cultural differences and reconciling them with objective findings is one of the challenges sleep researchers face as they embark on a worldwide initiative to optimize the management of insomnia. This project is one arm of the Worldwide Project on Sleep and Health (WPSH), a 20-year global mission to improve the treatment of sleep disorders under the aegis of the World Health Organization (WHO) and World Federation of Sleep Research Societies (WFSRS). A forum to launch the insomnia project was held at the joint