Colored bulbs, blue,red, black etc apparently have been found to disrupt sleep and normal vision due to the fact that thier eys see more of the color spectrum then we do. Meaning, we may see 7 shades of a color and they see 15. (Lucky iggies!).
Much more about that here- http://www.reptileuv.com/reptile-video.php?rv=understanding-lighting-part2-600&nav=h#top
Sooo. most of us use and recommend something called a ceramic heat emiiter, which puts out heat but no light. It also requires a ceramic socket fixture , which can be found in auto stores and pet stores. Walmart has them in hardware for about 10 bucks. Most pet stores have the ceramic heat emmiter but you can get them online too.