I've asked the same ??I do not have intense reactions to the sun yet, but have been told to keep out of it as much as possible, so I wear spf 45 year round,hats or visors and sunglasses. At 49, with hot flashes, long sleeves are tough to tolerate, so I keep a white shirt in the car to pull up over the arm that is exposed....Tinting on your car windows can help..You can get special permission from the state if there are restrictions on window tinting...Just ask your dmv for a medical exemptions form .
From my research, I think our sensitivity has something to do with our skin being the largest organ in our body. When exposed to sun, we tend to "burn" even as we tan. A sunburn is an inflammation of the skin. There is some kind of cellular change for everyone....But lupies need to avoid inflammation of any kind so we do not trigger our immune systems to fight it....Thus setting ourselves up for a "friendly fire" situation.That's why even those of us who are not affected dramatically should avoid over-exposure because it can possibly trigger a flare in our bodies confusion about fighting the inflammation and going after healthy parts too. I'm sure there is a great scientific explanation for this, but this is how I have been able to explain it to myself. I am open for further clarification or correction if anybody knows more.
So, do I stay in the house during daylight?? I probably should, but I don't. I love to garden, so I work on the shady side of the house and follow the shade around. I try to walk on the shady side of the street and have been known to use an umbrella on sunny days when out and about.
I teach driver education and spend most of my day in a car....Have tinting (light) on my windows, but also just added a mustang convertable to our fleet. I know I should probably not have the top down , but at my age and the joy it brings my students, it sure makes for a wonderful day....You can't beat a beautiful summer day with good tunes on the radio and driving around town "topless"

i'm sure I might pay someday, but I also feel that we need to make the best of every good day we have.......When I was first diagnosed, I was very frightened and felt that fun times were over. It scares me that this dumb thing will probably kill me someday....Then again, I could get hit by a bus tomorrow. So, I decided to take my meds, obey my doc's as best I can, live each day to it's fullest and watch out for buses!!! I have really done quite well ever since............Take care all. :d