The bulb simulates natural moonlight to allow nocturnal viewing without disturbing the animal's day and night cycle. The light emitted is bluish due to the use of blue glass. The heat generated by the bulb is minimal but enough to provide tropical night time temperatures. The lower wattage of these bulbs does not interfere with natural night drops in temperature. The lower wattage of these bulbs does not interfere with natural night drops in temperature. Pet care bulb for use with Reptiles, Amphibians and Invertebrates only! Exo Terra® Heat Lamps are available in daytime and nighttime versions, depending on the application needed for your specific animals. While the daytime heat bulbs emit visible light in combination with the correct infrared-A heat radiation to simulate sunlight, the nighttime bulbs emit the correct infrared-A heat radiation without visible light to simulate moonlight and thus not disturb the animals day and night cycle. The Exo Terra® Heat Lamps will allow your reptiles to thermoregulate their body temperature to achieve the optimal temperature for enhanced activity and healthy digestion of their food items. All the Exo Terra® Heat Lamps are manufactured in colored glass to increase the transfer of heat waves which makes them highly energy efficient. Reptiles are ectotherm and thus need a specific ambient temperature, in order to thrive. The Exo Terra® Heat Lamps increase the ambient temperature and provide heat gradients for thermo-regulation. The Exo Terra® Heat Lamps not only increase the ambient temperature, they also emit infrared-A heat radiation, which penetrates the skin much deeper to increase blood flow and aid in natural cellular regeneration. The Infrared-A provided by the Exo Terra® Heat Lamps will also aid cell growth, wound-healing, promote the immune system, protect against UV damage, and stimulate many other biological processes.