LUSARAP

Deepsleep battery saver constantly puts the device to deepsleep mode while screen off.
LifeHacker: "Plenty of apps save your battery life, but this one takes the idea to a whole new level"

During deepsleep mode, Wifi, 3G are turned off, background apps are stopped. Therefore, most apps are not working, including Facebook, Google Service, etc,. It then constantly wakes up in order to download email, sync Facebook status, etc,. Its defined by deepsleep frequency and woke up duration