Sleep mode
The suspend mode (also know as Suspend-to-ram) is one of three power-saving modes for the ThinkPads. In this mode, the LCD screen (and the external monitor, if attached) is turned off and all tasks are stopped and stored in memory in order to save power. You can enter this mode by pressing FnF4 or by configuring your computer to enter standby mode automatically after a chosen duration of inactivity. The computer can also go into suspend mode when closing the lid, unless it has been set up not to. This may be useful when you are working with an external monitor and you want to close the lid without going into suspend mode. When in suspend mode, the suspend indicator light be turned on. To resume operation, press Fn.
Some ThinkPads also have the RediSafe suspend mode. This mode requires the presence of a hibernation file. To protect your work when you run out of battery power, this mode writes the status of the system to the hibernation file on the hard disk. Similar functionality can be achieved using Software Suspend 2, by setting PowerdownMethod 3 in /etc/hibernate/hibernate.conf.
See How to make use of Power Management features to learn about getting suspend mode and other power-saving modes to function on a ThinkPad running Linux.
See also
External resources
Using and understanding the IBM ThinkPad advanced power management features
