Later functionality was updated with Nokia Sleeping Screen app for last generation of Symbian smartphones (Nokia 808 and other) with features like custom standby screen from any image, and two themes for and 4 themes notifications design.
[5] The Always-On Display feature does consume energy, although the Samsung Galaxy S7 series phones, and later phones that made the feature popular are built with AMOLED screens in which no power is needed for black pixels.
[6] On LCD displays, the backlight has to be turned on, even if only a part of the screen is showing information, so this feature consumes a significant amount of power compared to a notification LED.
Typically, an ambient display solution which turns on the screen only when notifications are present, remains on, but turns off when they are dismissed will consume the least amount of battery power while still drawing the user's attention when required, in contrast to an Always-on Display which will keep the screen on, all of the time, to show some information, even if notifications may not be present.
In some phones, the Always-On Display/Ambient Display feature can be toggled on a schedule, such as during nighttime, or when the proximity sensor detects that the device is in a pocket.