[procedure] sleep [x]

Bigloo: sleeps for x microseconds.

Chicken: Puts the process to sleep for x seconds. Returns either 0 if the time has completely elapsed, or the number of remaining seconds, if a signal occurred.

MzScheme: causes the current thread to sleep for x seconds.

SRFI-18 and SRFI-21 have thread-sleep!.

Gauche has sys-sleep.

[procedure] sleep x

STklos: the argument is mandatory.