I'm no expert as I have no children yet, and have never been an academic teacher (coached competitive gymnsatics for many years though). But I've done a lot of reading and given a lot of thought to the subject of education, since I absolutely hated school, and don't want my children having to spend most of their waking hours doing something they dislike and haven't got the faintest interest in. My number one conclusion is that my kids will do NO homework before high school, and even then not much.
Did you know that studies have found no correlation between pre-high school homework and academic achievement? I'd recommend the short book "The End of Homework". Articulates the whole problem very well -- destruction of family life, disengagement of kids from family/church/community/informal play activities, as they constantly labor under the burden of homework assignments, complete elimination of parents' role in choosing what children should learn and how fast, conditioning kids to be workaholic adults who constantly bring job-work home with them. Schools need to get the message that they need to get all academic work done during the school day. Cut out all the garbage that most schools waste time on, and that would be no problem. It's simply absurd to pretend that a child needs to spend more than 6 hours a day on academics.
Many years ago, a school friend of mine who was the daughter of a British diplomat was sent off to a good boarding school in England, after her parents were appalled with the American public school where she spent one year (also the only year I ever went to public school). In letters, she told me all about her new school, and the most interesting thing, which I'd never heard of before, was that students were absolutely prohibited from taking books or other academic materials back to their dorms with them in the evening. There were scheduled periods during the school day called "preps" (basically study hall), when students were to study and do assignments, with one teacher on hand to help if they really got stuck on something, and they had to learn to get their academic work done in that time. A very good lesson for adulthood IMO, and a policy that would do wonders if implemented in the average American family and school.
As for your son's dislike of lighting for studying, does he have a single light on his desk, with the rest of the room dark, or just everything dark? If the former, it does tend to keep attention focused on what's on the desk. If the latter, well it's a little odd, but if it works I wouldn't worry about it. I've found that as I get older I need much more light to see clearly, so what would seem like insufficient lighting to me, would probably be plenty for a teenager.
I was reading a book written by a special ed teacher several months ago who referenced a problem that sounds similar to this. Some children have trouble reading because of the contrast between black print and white paper. Glare from lights exacerbates the problem. The teacher used different colored transparent sheets over the white paper to help these kids. Most children did better when one particular color was used but I don't recall which color it was. Sorry!