How long can a leopard gecko last without heat?

Leopard geckos native area's include: Pakistan, Iran, Saudi Arabia, Iraq, Afganistan. They live in temperatures ranging from 80-105F depending on season. These animals cannot survive for long without the temperatures reaching 80 minimal as a basking spot(2-5days max). A lot of people reccomend a heating mat with 2 or more inches of substrates so the animal cannot burn it's underside. A heating mat will keep your tank regulated at all times, incase of times without light.