Reptiles are ectothermic vertebrates, meaning they do not produce enough heat through thermogenesis and must rely on the temperature of their environment to maintain their body temperature. They regulate their body temperature through thermoregulation mechanisms, and when they are unable to maintain an optimal body temperature due to unfavorable environmental conditions, they enter brumation. Brumation is a physiological state of reduced activity or rest in reptiles, primarily seen in species of temperate and subtropical climates, characterized by a decrease in metabolism. A drop in environmental temperature and a decrease in daylight are the main drivers of this process, but in subtropical and tropical species, dry and rainy periods can also trigger it. Before the beginning of brumation, the animal's appetite decreases, and it seeks out a suitable hibernaculum. During the brumation process, metabolism, heart rate, and breathing slow down. The end of brumation is triggered by an increase in environmental temperature and daylight. In species of reptiles that brumate in nature and are kept in captivity, proper brumination reduces the risk of complications during or after the process. The most common complications are stomatitis, kidney failure, anorexia, refeeding syndrome, constipation, injuries caused by an attack, damage from frost (frostbite), and non-obstructive dystocia. Carrying out brumation in leopard geckos and bearded agamas kept in captivity has a positive effect, as it stimulates reproduction and enables the expression of species-specific behaviors.