Sleep on it (K2 #64)

Question of the Week
When I turn off my Windows laptop, I noticed options for Sleep and Hibernate. What is the difference between the two?
— Nawang S., Motithang

Answer
Dear Nawang,

Shut down, sleep, hibernate... Let’s try and sort things out. We’ll start with the most familiar option: Shut down. When you shut down your laptop, all your applications close, and then the laptop turns off. In this “off” state, the laptop uses no power, so the battery can keep for days. When it’s time to use the laptop again and you power on the laptop, Windows restarts (which can take a minute or two – or five) and then you need to re-launch your applications, like MS Word or your Internet browser.

Now let’s talk about sleep. In sleep mode the computer starts dreaming. OK, just kidding. In sleep mode (previously known as Standby), the screen and other power-hungry parts such as the hard disk are turned off, but the computer’s memory — where the running applications are kept — is still powered. This allows the computer to wake up very quickly – usually in a matter of seconds – and snap back to where you left it off, applications and all. In sleep mode, the computer uses little power but it still slowly drains the battery. If you are not using your computer for a few hours, or if the laptop is plugged into power, this is usually a good choice.

Finally: Hibernation. Somewhat like hibernating bears (but not all of them – sloth bears do not hibernate!), this is similar to a deep sleep. Hibernating the computer and waking up from hibernation takes longer than putting it to sleep and waking it from sleep, but when it wakes up, eventually it restores to where you left off. Why use hibernation? Under hibernate mode, the battery can keep for days. Here’s how it works: When you hibernate your computer, the content of the memory – where the running applications are kept – is first saved to the hard disk, and then the computer shuts down, so the laptop uses no power. When you turn the computer on, it restores the memory back from the hard disk. This is why waking up from hibernation takes longer than waking up from sleep. Hibernate mode is useful if you know your computer will be disconnected from power for a day or more, but you still want to kick off exactly where you left off.

The proper way to shut down
If you pull out the power cord or otherwise turn off the power while Windows is still running, this may result in corrupted files and other unexpected trouble. It is best to first shut down Windows, then turn off the power to the computer.