If you’re sharing your computer’s resources, such as a shared printer or iTunes playlist, you can set your computer to wake from sleep when other users access those resources.
To use this feature, you need an Apple wireless device that supports 802.11n, with the latest firmware installed.
To share your computer’s resources when it’s in sleep:
Choose Apple menu > System Preferences and click Energy Saver.
Open Energy Saver preferences
Select “Wake for network access.”
When this option is selected, your computer wakes at the following times:
When a user at another computer accesses your computer’s shared resources.
At regular intervals so that your computer can notify other computers on the network that its resources are available.
*If you have a portable computer, selecting this option will wake your computer only if it’s plugged in and the display is open.*