All sleep experts will say that darkness is key. If you want light for your book, use the overhead lights or get a mini book light or get an iPad or the Kindle White.

Of course, I am speaking from my POV as I like it dark for sleeping and I find it overall more relaxing than the "stark, harsh fluorescent lighting" as Capebretonboy called it (which I agree). I find the eye covers annoying... much like you find the overhead lights not adequate.

Again, there will never be a 100% consensus on this and I think AC and most/all other airlines have gone with what they think the majority of their passengers want: darker.

I usually am in J for long hauls and I do choose the window... the shade is open for takeoff and landing and the occasional peak outside but usually it's shut. I fly most of the time for business so my goal is as much sleep as possible.