Effects of sleep-promoting factor from human urine on sleep cycle of cats.

Slow-wave sleep (SWS) and rapid-eye-movement sleep (REM) were recorded in cats for 32 h a) under control conditions, b) following intraventricular infusions of artificial cerebrospinal fluid (CSF), and c) following infusions of sleep-promoting factor S prepared from human urine (SPU). During the first 12 h after receiving artificial CSF, the cats slept 4.9 +/- 0.2 h in slow-wave sleep (SWS) and 1.4 +/- 0.1 h in REM. Similar values were obtained from the same cats under control conditions. After infusions of SPU, the duration of SWS in the same cats increased to an average of 6.9 +/- 0.5 h with no significant change in REM averaged over 12 h; a transient decrease of REM in the first 4 h was fully compensated in subsequent hours. The increased SWS induced by the sleep-promoting factor from human urine subsided after 12 h, and there was no compensatory increase in wakefulness during the subsequent 20 h. The normal sleep cycle was not affected. In cats, therefore, the primary effect of SPU is to increase normal SWS, with little effect on REM.