Your Apple computer runs on electricity and even if you have enough to pay for just letting it run all day even if you are not doing anything, be prudent enough to conserve resources and save energy that could otherwise be utilized by other people doing more important things. You Mac makes it easy for you – just use the Mac Energy Saving options build into your system preferences.
Do your part for the environment by saving energy.
The Energy Saver preference pane in OS X Lion helps you do that by automatically letting the computer go to sleep after a certain period of inactivity. Not only that, you can also program it to wake up at a certain time so that it is ready for your use. You can do all that with the Mac energy saving options.
To configure your settings, go to System Preferences and click Energy Saver. Pull down Settings For and choose whether you want to configure for when your MacBook runs on Power Adapter or on Battery. You can select either Better Energy Savings, Normal or Better Performance for Optimization. It is up to you to select which is your priority. Better performance will of course be at the expense of a shorter battery life.
If you prefer to customize your settings on when the display and the computer goes to sleep, simply move the sliders to your desired time.
If you would like the computer to sleep or wake up at a certain time, click the Schedule button at the lower right of your pane. A new dialogue box will open. Check whether you want to configure the wake or the sleep. Pull down how often you want the computer to wake up / sleep and set the exact time. Press OK to apply your settings.