Sleeper is a small utility program developed by PassMark Software to help test the ability of PC systems to enter and recover from sleep and hibernation. It has been designed to work with PassMark BurnInTest but will also work with 3rd party applications. Sleeper allows you to put a PC into any sleep state (S1, S2, S3) supported by the system or into hibernation state(S4). Also wake the computer after a specified period of time. And put a PC to sleep or hibernation from the command line.