If you do not have the Resource Kit, you can use the following alternative to the Sleep command:
@ping -n Times 127.0.0.1>nul
where Times should be approximately the number of seconds you wish to delay plus 1.
The valid range of Times is 1 to 4294967295.
This process consumes very few resources.
To Sleep for 15 minutes (900 seconds):
@ping -n 901 127.0.0.1>nul