Dark Adaptation and Night Vision

he eye adjusts to darkness slowly — full dark adaptation takes many minutes — and loses it instantly to a bright light. That asymmetry defines night driving:

• A single oncoming high beam doesn't just dazzle in the moment; it resets your adaptation, leaving you effectively night-blind for seconds after the vehicle has passed. That's why the "look up and slightly left" technique matters, and why your speed should drop when you're dazzled.
• Your own cabin lights or phone screen sabotage adaptation the same way — a glance at a phone at night costs you seconds of road vision on top of the distraction itself.
• Age slows adaptation and reduces low-light sensitivity — a real factor for older drivers at night.

The habits follow directly: keep the dashboard dim, never look at bright light sources while driving at night, and give your eyes time after entering darkness — pulling out of a lit petrol station onto a dark road, you are briefly under-adapted, so ease into it.