Extending Daylight Could Boost Health

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.

Countries across 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 — often in late October or early November — 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.

Hillman conducted a study focused on Scotland, the northern-most part of Britain, which found that switching to Central European Time — to Greenwich Mean Time plus one hour (GMT+1) in the winter and GMT+2 in the summer — would give most adults 300 extra hours of daylight a year.

A "lighter later" campaign in Britain has gained support from many of the country's major sporting bodies.

Writing in the British Medical Journal, Hillman said research shows people feel happier, more energetic, and have lower sickness rates in the longer, brighter days of summer, whereas moods and health decline during duller days of winter.

Dr. Robert Graham of Lenox Hill Hospital in New York said leaving clocks alone in winter should be considered to encourage people to get out more and get more exercise.

High rates of chronic illnesses such as diabetes, heart disease, and obesity are caused in part by lack of exercise — adults are advised to do 30 minutes moderate or vigorous activity a day, and children at least an hour.

"As a society we are always looking for accessible, low-cost, little-to-no-harm interventions," he said by telephone. "By not putting the clocks back and increasing the number of accessible daylight hours, we may have found the perfect one."

A study published earlier this year found that advancing clocks by an hour in the winter would lead to energy savings of at least 0.3 percent of daily demand in Britain.

Elizabeth Garnsey, one of the study's authors and an expert in innovative studies at Cambridge University, said this was equivalent to saving 450,000 metric tons of CO2 during winter alone.