This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary hypothesis of this study is that insulin resistance/visceral obesity is a pathogenetic factor in obstructive sleep apnea and is a primary determinant of its clinical severity.