Three recreational cocaine users (age, 26.7 years), after one adaptation night, spent 5 days and nights in the laboratory where their EEG, EOG, and submental EMG were recorded during all of their sleep. On the second afternoon and evening of the study, subjects used an estimated 1 to 2 g cocaine intranasally. They all slept between 2:00 A.M. and 9:00 A.M. that night. Blood samples were drawn each evening and morning. Absolute plasma cocaine levels and patterns of elimination were consistent with subjects report of dose and time of administration. Mood ratings were made repeatedly throughout the study. There was suppression of REM sleep during the use of cocaine followed by a rebound which is specific to REM sleep and is not seen in other stages of sleep. REM variables subsided to normal levels on the third recovery night following cocaine use.