Hummer 2007 H2 Owner's Manual page 343

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 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 are driving, do not
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 re-adjust
to the dark. When you are faced with severe glare,
as from a driver who does not lower the high
beams, or a vehicle with misaimed headlamps,
slow down a little. Avoid staring directly into
the approaching headlamps.
Keep the 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 the headlamps light up far less
of a roadway when you are in a turn or curve.
Keep your eyes moving; that way, it is easier
to pick out dimly lighted objects. Just as the
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 are not even
aware of it.
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