Winter has receded, spring and summer are in sight. The cold, dark season's reign of listlessness would be over were it not for springtime lethargy.

The first warm, sunny days beckon, but many people feel tired and sluggish. The hour's sleep lost when clocks are advanced to summer time lowers energy levels further. Springtime lethargy can be beaten, though, according to Juergen Steinacker, professor of sports and rehabilitative medicine at Germany's Ulm University Hospital.

"Many people become inactive during the winter," he says. "They exercise less because of the bad weather and are also exposed to less sunlight." They not only feel less productive as a result, they are less productive.

"People lose about 10 percent of their productivity during the winter," Steinacker estimates.

There is only one thing that helps, he says: "Get out of the house!"

Taking a walk in sunshine and fresh air can be uplifting. People sensitive to the sun should not overdo it, however, since the bright light in the first days of spring can cause mild migraines. So wearing a hat and sunglasses is advisable, Steinacker says.

Workers often find it difficult to leave their workplace to get fresh air. They can go for a short walk during their lunch break, though. And those who tend to be "couch potatoes" should not plop onto the couch as soon as they get home from work, Steinacker warns.

Elderly people restrict their winter activities more than younger ones do, so their springtime lethargy is especially pronounced.

"We advise seniors to go outdoors nonetheless, but to stick to safe areas" such as the route to a neighborhood store or a park free of obstacles, he says.

In addition to getting lots of exercise, eating properly is important. "When it comes to diet, the old rules apply: It should be rich in vitamins. Eat a lot of fruit and vegetables - whatever is in season," Steinacker remarks. "Heavy fare should be avoided if possible."

People are mistaken if they think that getting more sleep will combat springtime lethargy. "Surrendering to your tiredness won't help," Steinacker says. On the contrary, you have to get your blood circulation going.