Abstract: The present invention relates to a device and method of reversibly activating photochromic materials within an enclosed vehicle using one or more ultraviolet (UV) sources located within the interior of a vehicle. Upon activation, such UV sources cause the photochromic materials to darken; upon deactivation, the photochromic materials revert to their clear state. The photochromic materials may form part of a pair of eyeglasses (10) containing photochromic lenses, thereby enabling their use as sunglasses within an enclosed vehicle. UV sources may be aimed at the photochromic target and may be automatically modulated using a photosensor in response to changing ambient light conditions. UV sources may be positioned in differing locations within the vehicle. A variety of different UV sources may be used.