The day/ night Dimming thermostat with the capacity to drop the temperature at night if attached to a timer or an optical controller. The function is the same as the standard Dimming thermostat but with the added facility of a night time temperature drop facility. With many species it is important to give them a cycle of warm day time temperatures and cool night temperatures. Many species would experience this in their natural environment. Through an additional mains input lead and via a time switch or a Habistat 'Night eye' (not included) the thermostat will lower the set temperature for a period of time set on the time switch or controlled by the 'Night eye' between 3 and 13 degrees Celcius lower than daytime temperatures. When used with the 'night eye' the light levels will be sensed and the temperature will automatically be switched down when it is dark, and back up again for the daytime. No more need to adjust time switches with the 'Night eye' as it automatically adjusts to seasonal changes.