The Windows Vista Hybrid Sleep is a new Microsoft approach to power management on laptops. Prolonging battery life, decreasing the total cost of ownership by reducing electricity costs and enhancing customer experience in the context of an energy efficient system were Microsoft's goals with the power management sub-system for Windows Vista.

"The Windows Vista power management goals were simple: 1) making turning a computer "off"/"on" as reliable, simple, and fast as turning off/on a TV, and 2) maximizing the active usage if on battery and reducing the energy consumption if on A/C power. The first goal involved not only improving the predictability of the behavior when a PC was switched "off", but more importantly changing the model for what "off" and "on" means," revealed Jim Allchin, Co-President, Platform and Services Division.

While in Hybrid Sleep, Windows Vista's state is saved both in RAM and on the disk, while the operating system is balanced between the sleep and hibernate modes. Vista Hybrid Sleep saves both the context and data as the system state is stored in RAM, as in "sleep" mode, but also via a hibernate image on the HDD.

"In order to ensure that "off" worked effectively with this new model, we needed to address some unpredictability that occurred with sleep in Windows XP. Instead of waiting for each application, service and device to agree before going into power saving mode, in Windows Vista we changed the approach so that we give the application, services and devices a notice of the impending suspend and then wait a maximum of 2 seconds for them to finish up any work and put themselves into a state they can continue from when the system wakes up," added Allchin explaining that unpredictable application behavior will no longer be an issue for laptops that go into power saving mode.