Hibernate mode is the best option for conserving battery life while also saving the user's session. When a computer hibernates, it writes the contents of its RAM to the hard drive and shuts down, consuming no power. Upon restart, the session is restored to its previous state, allowing for a quick resumption of work. Sleep mode, while it does save the session and allows for a quick resume, still consumes a small amount of power to maintain the session in RAM. Turning off the screen only is not a power state and will not save the current session; it only turns off the monitor. Full shutdown saves no session and requires a complete reboot, which does not allow for a quick resumption of work.