My Elitebook is currently winging its way back to an HP service centre, simply because its night light won't retract. The night light is located at the top of the screen, next to the integrated webcam, and can be useful for illuminating the keyboard in low light conditions.
HP says that this problem is a 'known issue', so it's essentially a design fault. It's very frustrating sending your laptop away for such a minor issue, yet an always-on nightlight is annoying and will un-necessarily drain the battery. My recommendation is to simply not use the night light, or at the very least contact HP support to see whether they will arrange a fix at a date that's convenient for you.
This integrated night-light is one of those features that seems like a good idea at first, but is an extra thing to go wrong and doesn't really compare to the fantastic back-lighting of the Apple Macbook Pro keyboard.