1998 GMC Suburban Owner's Manual - Page 221

Night Vision No one can see as well at night as in the daytime. But a s we get older these differences increase. 50-year-old A driver may require at least twice as much light to see the same thing at night as a 20-year-old. What you do in the daytime can also affect your night vision. For example, if you spend the day in bright sunshine you are wise to wear sunglasses. Your eyes will have less trouble adjusting to night. But if you're driving. don't wear sunglasses at night. They may cut down on glare from headlamps, but they also make a lot of things invisible. You can be temporarily blinded by approaching headlamps. It can take a second or two, or even several seconds, for your eyes to readjust to the dark. When you are f x e d with severe glare (as froma driver who doesn't lower the high beams, or avehicle with misaimed headlamps), slow down a little. Avoid staring directly into the approaching headlamps. Keep your windshield and all the glass on your vehicle clean -- inside and out. Glare at night is made much worse by dirt on the glass. Even the inside of the glass can build up a film caused by dust. Dirty glass makes lights dazzle and flash more than clean glass would, making the pupils of your eyes contractrepeatedly. Remember that y o ~ headlamps light up far less of a ~r roadway when you are in a turn or curve. Keep your eyes moving; that way, it's easier to pick out dimly lighted objects. Just as your headlamps should be checked regularly for proper aim, so should your eyes be examined regularly. Some drivers suffer from night blindness -- the inability to see in dim light -- and aren't even aware of it. 4-29