The AA says that because of reducing traffic flow, fewer accidents occur after dark than during daylight, but the proportion of fatalities is higher. The factors most commonly associated with night accidents are fatigue, inattention, the influence of liquor and reduced visibility. Depth perception is also reduced, resulting in impaired judgment and delayed reflex actions. After leaving a brightly lit place, it takes about 30 minutes before the human eye can see at 80 per cent efficiency, and up to an hour before night vision is at its best. Approximately 20 percent of adults have vision that is defective to some degree – from mild short – sightedness to night-blindness. Motorist who find that night driving is a severe strain on their eyes should consult a doctor or optometrist, who may recommend that driving after dark be avoided altogether.
Avoid keeping your gaze focused at a single distance, as this will increase eye fatigue. Glance about frequently, and take in areas at the edge of the area lit by your headlights. A poorly lit object is best seen if you focus your vision slightly to one side of it, as peripheral (outer) vision is less affected by poor light than central vision.
Speed should be reduced at night, so that you never drive beyond the range of your vision – that is, you must be able to stop under all circumstances, within the length of road illuminated by your headlights. Travelling with low or dipped beams, therefore, calls for lower speeds. Following distances should be increased at night and, unless you are about to overtake, keep the vehicle ahead at such a distance that it is just in the far limit of light from the dipped beam.
Headlights should be dipped well before an approaching vehicle is within range of the main beam. If the other driver does not respond, flick the beam back to high for an instant, and then dip. Resist the temptation to retaliate by keeping the high beam on – having two blinded drivers instead of one is merely doubling the risk. When approaching a vehicle travelling in the opposite direction while you are on a left-hand bend, dip the beam early, or it will sweep across the curve, blinding the other driver. On a right-hand bend, your headlights will shine outwards and away from approaching traffic, but if an oncoming driver dips his beam, it would be courteous for you to do the same.
Headlights need to be adjusted periodically, especially when a night trip is planned with the car loaded more heavily than usual. With rear-seat passengers and a laden boot, the dipped beam will be angled to shine too far ahead, and the main beam will dazzle oncoming drivers without properly illuminating the road. It may be advisable to have the adjustment done at a garage, and the beams should be reset when driving with the normal load. Tyre pressures should also be adjusted before loading a vehicle for holiday travelling.