EFFECTS OF PROMETHAZINE ON SLEEP STAGES IN CAT

Repeated observations of 4-hour sleep periods (AM and PM) were made in three male and three female cats. Minutes of total sleep time (TST), nonrapid eye movement (NREM), and rapid eye movement (REM) sleep were increased in PM trials. Percentage REM sleep was increased in PM trials. These increases in REM sleep are accounted for by changes observed in sleep cycle parameters, namely, a shorter time to the end of the first REM episode in PM trials, as well as longer REM episodes in PM trials. Promethazine hydrochloride (0.125, 0.25, 0.5, 1.0, and 2.0 mg/kg, sc) increased TST and NREM minutes (especially slow-wave sleep) in a dose-response relationship. Minutes of REM were decreased at the highest dose. Percentage REM sleep decreased at the three highest doses. These changes are accounted for by increases in time to the end of the first REM episode, cycle length, and time of onset of sleep to the end of REM episodes. No change in duration of REM episodes was seen. No differences in drug response with respect to AM or PM trials or sex were demonstrated. Promethazine decreased the total number of pontine-lateral geniculate nucleus-occipital (PGO) monophasic spikes during a trial run. There was no difference in frequency of PGO spikes when REM sleep occurred. © 1968.