Welcome to the Phylogeny of Sleep website. At this website, you will find the following:
- A searchable database of sleep characteristics on 127 mammalian species as of June 29, 2007;
- Information on current research projects including an edited book on the Evolution of Sleep and plans to test hypotheses on the evolutionary function of sleep;
- Information on the research team who produced this website;
- A list of relevant publications; and
- Supplementary information on data sources and data quality parameters for the core data set.
Click the links above (About the Database, Research Projects, Collaborators, Publications, Funding, and Resources) to learn more about what resources are available at this website.
Sleep is an evolutionary puzzle. Unlike activities such as sex, foraging and avoiding predators, the functions of sleep are not immediately apparent. While a certain optimal amount of sleep seems to be 'restorative' for most people, too much or too little sleep has adverse consequences for health and well-being. Each year, sleep disorders add an estimated 15 billion dollars to the national health care bill (Walsh & Engelhardt, 1999). Additional costs to society include lost worker productivity, accidents both on and off the job, and major health problems such as heart attack and stroke. About 70 million Americans suffer from a sleep problem; among them, nearly 60 percent have a chronic sleep disorder. Sleep problems affect men and women of every age, race, and socioeconomic class.
Despite the costs that sleep problems impose on the lives of millions of Americans, basic questions about the functions and evolution of sleep remain unanswered and understudied. At this site, you will find a database of sleep measures across hundreds of mammalian species and a number of other resources. The purpose of this Research Group and this website is to facilitate investigations into potential adaptive functions of sleep. Our group's overall hypothesis is that the two major mammalian sleep states REM (rapid eye movement sleep) and NREM (non-rapid eye movement sleep) have distinct evolutionary histories and physiologic functions. Investigation of the separate evolutionary functions of REM and NREM would clarify the role of each in basic restorative capacities of sleep and would illuminate the ways in which breakdowns in each sleep state could lead to distinct clinical disorders.