Greece and the entire EU returned to winter time on Sunday, when clocks at 4:00 a.m. were turned back one hour to 3:00 a.m. giving everyone an extra hour of sleep.

Winter time will revert back to summer time on the last Sunday of March 2012.

Winter Time is not considered such a good idea, anymore, though. Putting the clocks back in winter is bad for health, wastes energy and increases pollution, scientists say, and putting an end to the practice in northern areas could bring major health and environmental benefits.

A lot of countries (Europe, the United States, Canada and parts of the Middle East) mark the start of winter by ending Daylight Saving Time (DST) and putting their clocks back by an hour, at this time of year, a move that means it is lighter by the time most people get up to start their day.

But this also robs afternoons of an hour of daylight, and some experts argue that in more northern regions, the energy needed to brighten this darkness, and the limits it puts on outdoor activities are harming our health and the environment.

Leaving clocks alone as winter approaches would allow an extra hour of daylight in the afternoon and could boost levels of vitamin D as well as encourage people to exercise more.

In some countries, such as Britain and Russia, politicians are being asked to consider parliamentary bills suggesting it's time for a change.

"It must be rare to find a means of vastly improving the health and well-being of nearly everyone in the population -- and at no cost," said Mayer Hillman of the Policy Studies Institute in Britain, where a bill on DST is coming up for consideration in parliament soon. "And here we have it."

Almost half of the world's population has lower than optimal levels of vitamin D, often called the sunshine vitamin. Vitamin D deficiency is a well-known risk factor for rickets and evidence suggests it may increase susceptibility to autoimmune diseases.