A retractable dimmer sleeve comprises sleeve material formed into an elongated enclosed passage having an open end and an interior volume for receiving an elongated light source. The dimmer sleeve enables, during operation of a light source while received within the sleeve, adjustment of a length of a selected portion of the light source that is occluded by the dimmer sleeve so that only a fraction of light emitted by the light source escapes the dimmer sleeve. The apparatus may further comprise an elongated light source at least partially enclosed by the dimmer sleeve. A method comprises: enclosing at least a portion of the light source with the retractable dimmer sleeve; and moving, during operation of the light source while received within the sleeve, an end of the dimmer sleeve along the light source, thereby adjusting a length of the light source that is occluded by the dimmer sleeve.