SleepTime

SleepTime is an easy-to-use application that allows you to set a timer to put your Mac on sleep mode; this tool comes in handy whenever you are watching your favorite movie or you are waiting for a download to finish and you don't want to let the Mac run all night long.

Once you launch the program, you will notice that its icon appears on the status bar; all you have to do in order to use this software is right-click over the application's button, select after what amount of time you wish to put your Mac on sleep mode and let the program get its job done.
Afterwards, a timer will appear on the status bar letting you know how much time is left until it automatically puts your Mac on sleep mode.

The application comes with predefined timers, but you can add your owns by simply clicking over the "Custom" button and enter the number of hours and minutes.

Additionally, you will also be able to block your Mac from going automatically on sleep mode; this feature comes in handy whenever you are waiting for an installation or download to finish.

To sum it all up, SleepTime is a useful program that enables to set timers to put or prevent your Mac from going on sleep mode.