GMC SIERRA 1994 Manual page 189

Nighf Vision
No one can see as well at night as in the daytime. But as we get older these
differences increase. A 50-year-old driver may require at least twice as
much light to see the same thing at night as a 20-year-old.
What you do i n 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
headlights, but they also make a lot of things invisible.
You can be temporarily blinded by approaching lights. It can take a second
or two, or even several seconds, for your eyes to readjust to the dark. When
you are faced with severe glare (,as from a driver who doesn't lower the high
beams, or a vehicle with misairned headlights), slow down a little. Avoid
staring directly into the approaching lights.
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 contract repeatedly.
Remember that your headlights light up f i r less of a 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 headlights 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.
4-25