When I was still working in the pet store industry I personally stopped at least 5 people at the register while they were checking out to make sure they understood how Hot Rocks were to be used.
Should you choose to use Hot Rocks in your enclosure you must understand very clearly that they are not to be used as a primary or singular heat source. If you in fact use them as such, you will undoubtedly join the ranks of those who have injured reptiles. To prevent this use an overhead heating source in conjunction with the Hot Rock. This way the ambient temperature will increase as well rather than just the one spot.
When it comes to overhead heating elements there are essentially three different “styles” to choose from. Red incandescent lights are likely the most popular due to their reputation of being able to be left on at night and not
disturbing the normal circadian rhythm of reptiles. Then comes Frances M Baines article in Reptiles Magazine which stated that some reptiles can actually see the red wavelengths of the light spectrum. Upon further research I learned that a lot of reptile species can see the red wavelengths in light and that basically the use of the red incandescent bulbs was actually akin to keeping our reptiles in a perpetual sunset like environment. Obviously this would disturb their natural circadian rhythm.