Photosensitivity

Photosensitivity is a medical condition in which a lifeform is sensitive to light.

The neural parasites encountered by the USS Enterprise (NCC-1701) in 2266 were found to be extremely photosensitive. Visible and ultraviolet light were both fatal to the organisms. 

The Night Aliens were an extremely photosensitive species. Native to the Void region of the Delta Quadrant, the species' physiology evolved to survive in complete darkness. When one of the species was being treated in the sickbay on board the USS Voyager, The Doctor needed to dim the lights in order to accommodate the needs of the alien.