The amount of carbon dioxide emissions potentially saved from going to bed an hour early was the equivalent of 20 per cent of annual emissions from household lights, "Many Japanese people waste electric power at night time, for example by watching TV until very late," a ministry spokesperson told The Daily Telegraph.

"But going to bed early and getting up early can avoid wasting electrical power which causes carbon dioxide emissions. If people change their lifestyle, we can save energy and reduce emissions." The campaign also proposes that people take advantage of an extra hour of morning sunlight by improve their lifestyles in general by running, doing yoga and eating a nutritious breakfast.

It is the latest initiative tackling climate change by the Japanese environment ministry, which is faced with the challenge of reducing carbon dioxide emissions by 25 per cent from 1990 levels within the next decade.

It was the same government department that launched the high profile Cool Biz campaign five years ago, which encourages workers to wear short-sleeved shirts and offices not to turn air con lower than 28 degrees during the summer.