100 Ways to Reduce Your Impact

Step 25 Computer sleep mode and hibernate mode

Enable the "sleep mode" feature on your computer, allowing it to use less power during periods of inactivity. In Windows, the power management settings are found on your control panel. Mac users, look for energy saving settings under system preferences in the apple menu.

Configure your computer to "hibernate" automatically after 30 minutes or so of inactivity. The "hibernate mode" turns the computer off in a way that doesn't require you to reload everything when you switch it back on. Allowing your computer to hibernate saves energy and is more time-efficient than shutting down and restarting your computer from scratch.

Thanks Natural Resources Defense Council for that tidbit of information.