Many captive reptiles do fine with a slight temperature drop at night (that is what many experience in the wild). Many reptile care sheets recommend a night time or minimum temperature. A slight gradient can still be provided, again to let the reptile choose where it wants to be.Ultratherm under tank heaters, or "heat pads", use a low wattage density heat element. Essentially this means the element does not get very hot and uses very little electricity. Typically you can expect a surface temperature on these heaters to reach about 90-95 degrees Fahrenheit in an average room temperature.