Do you know anyone who keeps sunlight out of their house 24/7?

I have a relative who does, even during daytime parties, any time of year. All the shades are drawn and the lights are on and if I open a shade, they go behind me and close it. What in the world? Why would someone do this? I have seasonal affective disorder and I can't stand visiting them because I can't have an ounce of daylight for the duration.