Driving in the dark

End of Daylight Savings Time increases risks

Shorter days, fatigue, compromised night vision, rush hour and impaired drivers are some of the risks we face when driving at night. These risks become especially pronounced moving into the weekend, with fatal crashes peaking on Saturday nights, according to a National Safety Council analysis.

When Daylight Saving Time ends at 2 a.m. Sunday, Nov. 5 – many people will find themselves spending more time driving in the dark. When you are driving at night, depth perception, color recognition and peripheral vision can be compromised, and the glare of headlights from an oncoming vehicle can temporarily blind a driver.

Night driving is dangerous because, even with high-beam headlights on, visibility is limited to about 500 feet (250 feet for normal headlights) creating less time to react to something in the road, especially when driving at higher speeds.

NIGHT VISION LESS ACUTE
Humans are born with two types of photoreceptors in their eyes: rods and cones. In the daytime, we utilize cones — the structures that allow us to see color. With the onset of night, however, we shift to a mix of rods and cones; in very, very low light, we rely entirely on rods — which is why, in the darkness, everything appears black and white. While your vision in daylight may be just fine, night vision becomes less acute. In people with age-related macular degeneration, this process is even more pronounced.

At the same time, our pupils, which regulate how much light enters our eyes, shrink with age. Even for the same light level, there’s less light getting inside our eyeball. By the time we hit our 60s the backs of our eyes are receiving only one-third the light they did when we were 20.

What’s more, by the time we reach our late 50s, nearly one in 10 will suffer from cataracts — a blurring caused by a buildup of protein on the disc-like lenses behind our pupils. By the time we hit our 80s, more than half of us will have cataracts.

HALF OF ALL FATAL CAR CRASHES
Older drivers — in 2020, there were some 48 million licensed drivers over 65 in the U.S. — tend to “self-regulate,” studies show, and they take themselves out of driving in riskier situations. The most common safety choice older drivers make is not to drive after dark. With good reason. Half of all fatal car crashes happen after dark, according to data from the National Safety Council — even though only 25 percent of driving happens then. Drivers are less likely to wear seat belts at night, are more often under the influence of alcohol,  and more prone to be fatigued.

Night vision is the ability to see well in low-light conditions. As we age, we have greater difficulty seeing at night. A 50-year-old driver may need twice as much light to see as well as a 30 year old. At age 60 and older, driving can become even more difficult, according to the American Optometric Association (AOA).

The AOA recommends older drivers:

• Have annual vision exams.
• Reduce speed.
• Minimize distractions, like talking with passengers or listening to the radio.
• Check with your doctor about side effects of prescription drugs.
• Limit driving to daytime hours if necessary.