If you need to see in the dark, don't look straight ahead

The eye has 7 million cones that are sensitive to bring light and 125 million roads that are sensitive to low light. The cones are in the fovea (central area of vision) and rods are less central. So if you're in low light, you'll see better if you don't look right at the area you're trying to see.

From Susan M. Weinschenk's book "100 Things Every Designer Needs To Know About People".