The council says it has no choice but to switch off the lights
Timer switches are to be installed on thousands of street lights in a bid to save a local authority money
Councillors in Torfaen have decided to put timer switches on 35% (or 4,600) of its street lights.
It would mean that the affected lights would be switched off between midnight and 0530 GMT.
A further 5,940 street lights in some residential areas and along some roads are also planned to be switched off. People have until January to comment.
Installing the timers will cost a one-off payment of £60,000 but will provide a yearly saving of £160,000.
Torfaen Council, like other authorities in Wales, is switching off street lamps to save both money and energy.
Overall, its whole package of measures will save about £450,000 a year.
As well as switching off the 4,600 lights between midnight and 0530 GMT using timers, the council is planning a phased switch off of another 4,140 lights in some residential areas from next spring.
And another 1,800 street lights will also be switched off along the county's main A and B roads in a programme to begin in January.
The moves equates to two in every three of the county's lights being switched off.
The authority says main junctions and roundabouts would stay illuminated under the changes.
Councillor John Cunningham, executive member for operational services, said: "We are left with no choice but to approve these measures because of the budgetary and environmental pressures.
"We believe the measures are the best possible outcome under the tough financial circumstances we are faced with.
"Again, I would like to emphasise that no residential area will be plunged into complete darkness."
It cost £400,000 to power Torfaen's 13,344 street lights in the last financial year, a figure which is estimated to reach about £900,000 in 2009/10.
The council said it does not want to pass the spiralling cost of powering the lights on to the taxpayer.
It said it was also committed to reducing its carbon footprint and said switching off lights would save 8% of its annual emissions.
Until 31 January 2009, residents can have their say about where lights should be switched off in residential areas by taking part in a consultation.
Times and venues of public exhibitions and more details about the proposals, including names of the A and B roads affected, will be included in the January edition of the council newsletter, Torfaen Talks.
Residents can also take part in the consultation online, contact their local councillor or phone the council's contact centre.
Powys Council has also decided to switch off two-thirds of its 14,000 lamps.
But town councillors in Llanfair Caereinion have agreed to pay the local authority to turn about 50 of them back on.
And one villager in Llangynog near Oswestry has paid £277 to have 15 lights switched on back between December and March.
Pembrokeshire is also considering switching off non-essential street lights after midnight.