|7 W night light|
In the past I have purchased three packs of electroluminescent nightlights for around $10-$12 and they tend to last several years before they eventually grow dim and become relatively useless. I tested one of these lights and found that it draws .033 W for an estimated cost of about 2.5 cents/year. A few days ago I was in the hardware store and saw a two pack of blue LED nightlights selling for under nine dollars and thought I would try them out. LEDs draw a little more power at .125 W for an operating cost of around $.10/year. LEDs are typically rated to last 30,000 to 50,000 hours so I expect these to last 3 to 5 years.
Here are some comparison images of LED (top) and electroluminescent (bottom) with ambient lighting and lights out:
|LED vs electroluminescent night light in ambient light|
|LED vs electroluminescent night light in the dark|
The LED is significantly brighter and cast a visible pool of light in a dark hallway, while electroluminescent ones are just enough to see by, similar to moonlight coming through a window.
There are other types of night lights that contain light sensors and motion sensors so they turn off when they are not needed. I suspect that those that use a motion sensor consume a fair amount of power even when they are off just to maintain the motion sensor. (they do, see this blog post). I leave mine on all the time since their cost to operate is so trivial.