Sleep Timer is a Widgets software developed by James M. Allen. After our trial and test, the software is proved to be official, secure and free. Here is the official description for Sleep Timer:

This Widget lets you set a timer to put your computer to sleep. Once the timer has elapsed, your computer will either go to sleep (aka hibernate/standby), log off, Shut Down, or restart, depending on the option you choose.

Click on the bed to start the timer and to expand/contract the Widget while the timer is running. Click on the time when the timer is stopped to cycle through preset sleep times, or set the countdown time manually in preferences.