We can be grateful for electric lights these days, because reading by candlelight or firelight is both difficult and bad for the eyes. The flickering light creates shadows that force you to slow down to see words clearly, and the level of illumination is so low you’ll probably strain your eyes trying to make out the letters on the page. On the other hand, when the light is too bright there’s a glare coming off the page that will also stress your vision and make it hard to read. To make sure that you’re able to read smoothly and easily, whether that’s on paper or on a computer screen, you need to make sure that the level of light in the room is just right.

The contrast between background and text isn’t something you can adjust with a printed book, but the black-on-white print is generally easy to read. However, this contrast might be too much if you’re outside in the direct sunlight; reading on the beach will be easier if you’re sitting where the book is in the shade, and you’re wearing sunglasses. If you’re reading on a Kindle or laptop, you can change the contrast or the text size to make it easier to see.

If you’re in a dim room and can’t increase the overall light level, use an adjustable spot lamp to add illumination where you’re sitting. For printed material, you can focus the circle of light over your shoulder and directly down onto the page. With a computer display, you don’t want the light to be right on the screen, because that creates too much glare. Instead, angle the light from the side and across the keyboard so that the light isn’t in your eyes or directed at the screen.

If you use your computer at night, alter the color settings of the display so that they’re not as harsh, to reduce eyestrain. Tired and sore eyes lead to slower reading speed and increased mistakes in reading. There’s a utility called f.lux that will do this for you, adjusting the display for your local time zone; it’s said to help you sleep better, too, if you’re one of those people who fall asleep with the computer still on.