The invention relates to an ultraviolet radiation lamp. The lamp comprises a substantially sealed cavity comprising a mercury-containing material; a filament disposed in the sealed cavity; and an electrical control element in contact with the filament, the electrical control element configured to adjust or maintain a temperature of the mercury-containing material with respect to a prescribed temperature. Such a constructions allows the present ultraviolet radiation lamp to be operated at optimal efficiency without the need to use additional components to add heat to and/or remove heat from the mercury-containing material.