Instead of buying some battery sucking commercial night light, get a solar panel, a lightbulb (the smaller the better), a couple wires, and some hot glue.
Attach your wires accordingly to whatever connection your solar panel has and attach that to your small lightbulb. I mounted all this on a piece of extra wood (An average Instructable-er should have one). I didn't want the wood burning, so I hot glued the wires together onto a piece of glass and hot glued that to the board. Congratulations! You just saved yourself some money and now have a cool light. Be sure that whenever you're sleeping with this, face the light away from you so you just get soft light while you sleep at night.
The best part is that it requires no battery replacing and sockets are kept free if you happen to have any.