Light is fundamentally important when setting up appropriate habitats for animals such as reptiles, amphibians and insects. You should generally try and reproduce the photoperiod of the natural environments they come from. This encourages natural behaviour. For example, there are incandescent lamps which help recreate an effect similar to sunlight, others which reproduce a night light and emit heat. Then there are fluorescent lamps which provide reptiles and amphibians with the right amount of UV-B and UV-A to encourage their normal biological functions such as appetite, digestion, breeding and calcium assimilation.