Question: are night lights expensive to run?
Answer: Running Costs At 10 watts, an incandescent nightlight run for 12 hours will use 120 watts, costing 1.5p a night. ... For an LED nightlight, this works out to around 56p per year. In the UK, electricity is billed in units of one kWh, with the current price around 13p per kWh as of 2011.