By Marianne Knowles

Call it writer’s insomnia: You’re on a roll, writing for hours, late into the night. Finally, exhausted but accomplished, you save your work, back it up, switch off the computer, and fall into bed.

And then you stare at the darkness for an hour or more before finally nodding off. It’s so frustrating! You’re exhausted, so why can’t you go to sleep? Is your story too exciting? Are your characters too insistent?

Maybe. Or maybe it’s the blue light shining out of your computer screen and straight into your eyes.

Several recent scientific studies have demonstrated a connection between blue artificial light and insomnia. Early forms of artificial light — candles, campfires, and oil lamps — emit wavelengths only in the red, orange, and yellow parts of the spectrum. Sunlight contains the full range of visible wavelengths, from the longest (red) through the shortest (violet). Until…