Our houses are climate controlled for our comfort in most cases, and most humans are comfortable at about 70 F. Most reptiles are comfortable between 80 and 90 F, depending on the species, and many require it even warmer. Iguanas are a VERY hot species, for example, requiring very high temps to digest their food properly. Bearded dragons also require high temps for proper digestion. Reptiles also have exacting humidity requirements. A bearded dragon is really too small to roam free even in a climate-controlled room. Water dragons, monitor, iguanas, and tegus are a few animals large enough to require/do well in a room setup, but NOT a person's bedroom! They would need the room temperatures to meet THEIR needs, with a warm basking area, and controlled humidity levels, and in spite of some reports of house trained animals, it's really just that they tend to defecate in the same spot each time--you cannot housebreak them. What if he chooses your bed? What if he's stepped on and injured? If something falls on him? Give up the idea, it's a bad one.
If you really want a pet lizard, a leopard gecko or a bearded dragon are good choices but research your individual animal very carefully FIRST. Setting up a reptile properly can be expensive, and you cannot cut any corners. They must have certain things to survive in captivity, among them are heat, light, proper humidity, and proper nutrition. Keeping a reptile is completely unlike keeping a cat or a dog, or even a bird.