The light is unkind to John Kapellas. In fact, the light burns him.
Sunlight or artificial, a ray of sun or a shine from a smartphone's screen, light causes the 59-year old to break out in blisters, according to the San Francisco Chronicle.
This extreme form of photosensitivity means Kapellas rarely leaves a darkened San Francisco apartment.
This kind of affliction is extremely rare, the experts say. Usually, people with photosensitivity can cope with artificial light.
But not Kapellas, who used to run a window-washing business. He must block even the light from his microwave and refrigerator, according to the newspaper.
Doctors are unsure what caused his case, the newspaper reported. He has been HIV positive since 1988, and it is possible the disease or the combination of drugs he is on may had led to it.
He navigates his home using LED flashlights and candles, the newspaper reported, but still remains upbeat.