Reptiles are cold blooded meaning they require external warmth to thrive. When the ambient temperature gets too cold they simply shut down and go inactive. Where adapted to do so, this can be a strong survival tool to wait out the winter where they can re-emerge in the warmth of spring and summer. In the more tropical areas where the winter is mild, they can tune their habits to coincide with the sun and flourish all year long. As reptile keepers, it is our challenge to simulate those needs without direct access to the sun and often times in climates that are inhospitable to our reptilian friends.
In order to provide them with full spectrum lighting as the sun provides, we must first understand what exactly the sun contributes to their wellbeing, and also understand what dangers that presents. It might surprise you that sound and light have travel in much the same way, through waves. Deeper sounds have slow waves, higher sounds have faster waves. The distance between the peaks of each wave is its called frequency (how often the peak happens in a given time). Sound waves travel slowly and light waves travel much faster. Light spectrum is just a representation of high frequency.