The primary objective in this study is to test whether propranolol lowers glucose and free
fatty acid levels during sleep in obstructive sleep apnea (OSA), and preserves vascular
function (EndoPAT) versus placebo. The secondary objective is to test whether propranolol
influences sleep quality, architecture, and hemodynamics in OSA. OSA will be elicited by
temporarily discontinuing CPAP therapy in patients with a history OSA accustomed to CPAP
therapy (CPAP withdrawal).