Many televisions possess power-management features that allow them to turn themselves off when they've been left on for too long. This feature helps owners save electricity, and it preserves the television's screen.
Different televisions consume power at different rates. However, EnergyStar-rated televisions must consume 1 watt of energy per hour or less while in sleep mode. Often, this sleep mode is accompanied by an auto-shutdown feature that reduces that power consumption even further.
Like cathode-ray-tube televisions, plasma screen televisions can be damaged by being left on for an extended period of time. If the image on the screen remains static for too long, an afterimage may be left on the screen. This afterimage or 'ghost' can be visually distracting and is detrimental to daily viewing. Automatic power features can prevent this from happening.