Street lights on a Hampshire estate are being switched off after midnight as part of a trial aimed at reducing carbon emissions.
Judith Giles said crime on the estate has increased
But a Fishlake Meadows estate resident in Romsey said the blackout of 400 lights makes her feel unsafe and has caused an increase in crime.
Between 300 and 400 homes in 14 streets are part of the trial.
The county council said it is only one of several methods being trialled during a six-month period.
Judith Giles, who lives on the Fishlake Meadows estate, said: "We're not very happy at all.
"The residents in the area feel very unsafe when there are no lights on outside.
"They feel very insecure when they look out in the night and they can't even see their own garden.
"There are a lot of elderly people in the area, who live on their own, and this is causing them concern.
"There has been more crime over the last few weeks.
"Cars have been damaged, gardens have been damaged and we're frightened that as time goes on, it will get worse because people know there's no lighting in the area."
Mel Kendal, Hampshire County Council's cabinet member for the environment, said Romsey was chosen because the area has a very low crime level and the police were informed about the trial.
He said, they have so far only received three comments from residents - two favourable, one unfavourable.
He said the experiment was part of an examination of new lights and switching off times ahead of a new contract for 140,000 street lamps across Hampshire.
Other methods being trialled include using white lights, which are more energy efficient than yellow ones, and dimming the level of the lights.
Mr Kendal said: "We thought we would try different lights and different switch-off periods to see to what extent we could reduce our carbon footprint and overcome complaints about light pollution."