I would like to know the difference of hibernation and sleep mode on mac os x. I use macbook pro. Which one makes mac to completely turn off electricity from mac circuits along with keeping an image of current state of osx environment? A friend of mine told me that sleep mode is not so good to use, because electricity is present inside computer, while hibernation means that computer takes an image of osx state in hard disk, without keeping any power to the circuits, so it is preferable. My friend spoke with pc experience in mind, but I think that it should not be a different thing on macs. Is there hibernation option in osx? Is it safer/healthier for mac to use such option? I suppose that the less hours a machine is running, the better it is.