It really depends on exactly what you are talking about.
There is blue lighting that is used in SW
/Reef applications called actinic lighting. It is blue in color, though those bulbs probably aren't dim enough to be considered "night lighting".
The best way to add some night lighting or "moon lighting" as it is often called, is to added some strip LED
lights to your existing fixture. Something like Flexible LED Light - Waterproof Flexible LED Strips - LED Flexible Light for Sale - ElementalLED.com
would work very well. You just need a foot or 2 of this strip lighting, and a transformer to plug it into.