Abstract: A lamp (100) comprising: a housing (110) having a transparent portion (101); a light source (102) disposed at least partially within the housing (110), wherein the light source (102) is configured to emit light, in use, through the transparent portion (101) of the housing (110); and a heat transfer unit (103) disposed at least partially within the housing (110), the heat transfer unit (103) comprising a heater (105) and a fluid circulator (106), wherein the heat transfer unit (103) is operable in a first mode and a second mode; wherein in the first mode, the heater (105) is turned on, thereby heating a thermal transfer fluid contained within the housing (110), and the fluid circulator (106) is operated to circulate the thermal transfer fluid such that heat is transferred to the transparent portion (101) of the housing (110); and in the second mode, the heater (105) is turned off, and the fluid circulator (106) is operated to circulate the thermal transfer fluid contained within the housing (110) such that hea