If I’m writing for hours on end, my eyes are always killing me at the end of the day. It actually really helps if you set the page color to a mint green. It’s pale enough to make the black text easy to read, but the difference from white makes it strain your eyes much less!
You can change the page color by going to: Tools > Options > Appearance > Editor > Page
Hope this helps someone as much as it did me!
I find a light yellow is best, something similar to those yellow PostIt notes.
I do most of my writing in Compose mode, which I’ve set to a black screen and green letters–sometimes I switch them to Amber letters, depending on whether I’m in a revenant IBM or a Kaypro mood.
A quick keystroke, and I’m back to editing, or reorganizing, or researching fuzzy facts in the White World of Binderland. The contrast between the two screenscapes not only rests the old eyes, but reminds me to sit up straight and wipe that smile off my face and machete out all that clutter with the metaphorical blue pencil.
You shouldn’t be or at least not sitting for hours on end doing it. You need to take regular breaks that take you away from the screen and the chair. You risk more than your eyesight if you don’t follow health and safety suggestions.
Beats the BBC B, hands down
reepi-baby’s right-on there.
If you have a long-legged, voluptuous, blonde Nordic neighbour, ask her to come round for a minimum of 10 mins every hour, and stand behind you as she massages your aching neck muscles, and your tense forehead, as well as kissing each of your fingertips, at least the ones you use for typing. Of course, you’re on a winner if you use Dragon Dictate, cos she can kiss your lips instead. Mind you, keep the kisses chaste … no French kissing … tongue down the back of the throat, kindda stuff. 
Oh, that brings back memories. I had a Kaypro 10, with the monstrous 10MB hard drive. But the green screen has long been my favorite.