Why is my vision worse when driving at night?

If you’re concerned about your vision when driving at night, you’re not alone. In fact, the College of Optometrists reports that around four in ten people in the UK feel nervous about night driving, often finding it harder to spot hazards, judge speed or distance, or simply feel confident behind the wheel. Since many seem to experience these issues but rarely discuss them, we asked an expert to shed some light on why they happen.

Why driving at night feels different

Night driving can feel surprisingly different from daytime driving. Many people notice that navigating the roads becomes more challenging after dark and may start avoiding night driving altogether. It can be especially confusing when an eye test shows nothing unusual, yet you still feel that something has changed.

Mr Alex Day, a Consultant Ophthalmologist based in London, UK explains that night driving difficulties can be missed in standard eye tests, which use high-contrast black letters on a white background.

“However, real day-to-day life, particularly at night, is a low-contrast environment,” he says. “A person can have '20/20' vision on the chart but struggle significantly to distinguish a dark-clad pedestrian against a hedge.

“This discrepancy often leads to a loss of confidence - drivers may compensate by driving erratically, slowing down unexpectedly, or hesitating at junctions. This in itself can be dangerous.”

Mr Alex Day, a Consultant Ophthalmologist based in London, UK

As we get older, our pupils become smaller and less responsive, which means less light reaches the retina. The retina is a thin layer of tissue at the back of your eye that captures light and converts it into electrical signals for your brain to interpret as images.

Day explains that, for example, the retina of a 60-year-old receives only about one-third of the light that a 20-year-old’s retina does. He likens this to “driving with sunglasses on”.

“At the same time, the eye’s lens stiffens and begins to lose clarity - an early sign of cataract development - which increases the scatter of incoming light,” he says.

“This scatter can create starbursts or halos around headlights. Combined with changes in pupil size at night, the eye’s focus shifts slightly towards short-sightedness (myopic shift), blurring distance vision and making road markings harder to see clearly.”

Even if your vision seems perfectly normal during the day, it’s wise to schedule an appointment with your optometrist to ensure your eyes are healthy.

“You should never ignore a loss of visual field - such as failing to spot people or cars approaching from side roads until the last moment,” says Day. “In the context of night driving, if you are dazzled by oncoming headlights or your vision takes an unusually long time to return to normal, this suggests your eyes are struggling.”

He adds that frequently drifting out of your lane or clipping curbs are warning signs that your vision may not be safe for driving.

Certain health conditions and lifestyle habits can impact the quality of your vision, affecting how clearly you see both during the day and at night.

Day highlights several common causes of reduced vision:

• Health conditions - uncontrolled diabetes, for example, can cause the lens of your eye to swell, leading to fluctuating prescriptions that make night vision unpredictable. It can also contribute to early cataract development.

• Medicines - certain drugs, including antihistamines, antidepressants, and blood pressure medicines, can cause dry eyes. A dry ocular surface scatters light, significantly worsening glare.

• Fatigue - vision isn’t just about your eyes, it also relies on your brain. When you’re tired or stressed, your brain’s processing slows, making it harder to filter visual ‘noise’ such as glare and react to hazards.

Day warns: “Drivers who have had less than 4 hours of sleep in a 24-hour period have a crash risk that is approximately 10 times higher than those who had a full night's rest.

"Being sleep deprived is very similar to drunk driving.”

Discuss your concerns with a health professional if you’re worried about whether you’re okay to drive at night.

If you’re having ‘near misses’ or feel unsafe, Day urges you to stop night driving and seek medical advice.

“However, I would offer significant reassurance,” he says. “Age-related deterioration is not always a one-way street leading to giving up your keys. The most common cause of night driving issues is early cataracts, and cataract surgery is transformative - typically restoring night vision to a quality you haven’t experienced in decades.

“Similarly, treating dry eye or updating a prescription can often resolve the issue. Don't assume it's the end of the road, as it is often a mechanical issue we can fix.”

Day concludes by noting that many people are reluctant to talk about night-time driving issues, often due to fears about losing their driving licence.

“In reality, many causes are treatable,” he says. “While some degree of glare is normal at night, always mention this to your optometrist, who can assess if you have cataracts developing.”