Nightlights aren't good. You should consider a Ceramic Heat Emitter for heat. The light can mess with their sleep. They aren't that expensive, especially if you buy from petmountain.com.
I was looking at the pet store when I went to replace it and it was way too expensive and I needed one right away. I did just get a black light, the owner said it was outside of the spectrum they can see. But, I did start putting a little towel over him so he can't see the light either way. I will look into a CHE a bit later. Thanks