Turning off street lights on some urban roads is hindering attempts to reduce accidents, according to the AA.
Councils have been turning lights off on some roads between midnight and 5am, with Essex the latest county council to dim the lamps.
The AA said its research showed that night-time accidents in bad weather on 30mph urban roads had been slashed by 15.6% over the past five years. But where street lights have been switched off or are not present, the fall was just 2%.
The AA added that official statistics revealed that, on darkened 40mph built-up roads, accidents in the wet, snow or ice were down 21.8% where there was lighting, but only 5.2% where there was not.
It said that overall, from 2007 to 2012, a 19.6% reduction in road accidents along town and city roads where street lights were on shrank to 8.8% where drivers, cyclists, bikers and pedestrians travelled in darkness.
An AA/Populus survey of more than 24,000 AA members conducted in February and March found 78% agreed that local residents should be consulted before any midnight to 5am light switching-off decisions were taken.
AA president Edmund King said: "Worse accident rates on roads with street lights turned off or not present is an insidious threat that has crept in literally under the cover of darkness.
"Many local authorities based their risk assessment on police accident profiles for the affected roads. This had two huge drawbacks.
"Firstly and fundamentally, roads that are safe when lit can become unsafe with the lights switched off, but that is only shown when drivers, cyclists, bikers and pedestrians start to get hurt and killed.
"Secondly, with an extra casualty here and there, it is difficult to spot a creeping overall trend that might suggest something is dangerously wrong with a blackout."