There are several ways to keep your gerbil warm in the winter. The main way is to keep your own home environment at a nice warm temperature near 70 degrees F. For your gerbil, there are cage modifications you can make to add warmth. For instance, provide your gerbil with extra bedding to burrow into for warmth. If his water bottle tends to freeze or get cold, wrap the bottle to keep it insulated and at room temperature. Heating lamps can be used just make sure you use a reflective bulb type and not a full force bulb. Too much heat can make your gerbil sick. You can also use a pocket pet and pocket pet safe heating pad. These small animal heating pads can be placed under bedding to provide extra warmth. Talk with your Sugar Land, TX vet about using an animal heating pad to keep your gerbil warm.
More details here: https://staffordoaksvet.com/