PHP sleep() Function

Delay execution of the current script for 3 seconds:

<?php
echo date('h:i:s') . "<br>";

//sleep for 3 seconds
sleep(3);

//start again
echo date('h:i:s');
?>

Definition and Usage

The sleep() function delays execution of the current script for a specified number of seconds.

Note: This function throws an error if the specified number of seconds is negative.

sleep(seconds)

Parameter	Description
seconds	Required. Specifies the number of seconds to delay the script

Return Value:	Returns 0 on success, or FALSE on error. This function returns a non-zero value if the call was interrupted by a signal. On Windows, this value will always be 192, which is the value of the WAIT_IO_COMPLETION constant within the Windows API. On other platforms, the return value will be the number of seconds left to sleep.
PHP Version:	4+
Changelog:	Before PHP 5.3.4, this function always returns NULL when sleep has occurred on Windows.