Looking at the calendar, spring is officially here. Looking out my front door, it's another story. In the foothills of the Jizerské Mountains, the ground is buried under a thick shroud of snow with hardly a sign of spring.

It's not surprising that this time of year — so long on promise, yet so short on fulfillment — has its own syndrome, so-called jarní únava (spring fatigue), also known by its angsty-sounding German name of Frühjahrsmüdigkeit. Newspapers and magazines publish reams of articles every year about battling this cluster of seasonal symptoms that includes general enervation, fogginess and drowsiness often accompanied by uncontrollable yawning or headaches.

Prague immunologist Dr. Martin Nouza says that spring fatigue is brought on by factors including "long winters with little sunshine, smog with a surfeit of free radicals and a dearth of antioxidants in the diet." He estimates that at least two-thirds of the population in developed countries exhibit symptoms, and says prevalence is higher in urban areas and among women. "The typical woman in this country has two jobs: eight hours or more at work, and a second shift at home."

In the agrarian past, spring fatigue was due mainly to a depletion in the body's energy stores caused by dietary deficiency. Fresh produce simply wasn't to be had in winter, and by early spring, household supplies of dried fruit and pickled cabbage had dwindled away. Even today, with an almost unlimited bounty of fruits and vegetables available year-round, food's nutritional value is often diminished by sped-up hothouse cultivation, being picked underripe and stored for extended periods, and long transport times.

That's one reason to give our bodies an extra boost of vitamins and minerals to banish the sluggishness associated with this time of year.

"Our ancestors made a spring cure of young, fresh herbs, especially stinging nettles, dandelion greens and ground ivy," says Dr. Nouza. "Also beneficial was birch sap, tapped before the leaves appeared."

He adds that a good personal spring-cleaning regimen incorporates lots of liquids — at least three liters (six pints) a day of water or other fluids such as herbal and green teas, mineral water or diluted juices.

Two excellent spring tonics to revive body and soul are an old-fashioned spring soup and a crisp spring salad with a mix of fresh greens and herbs.

There are many variations on spring soup, but this one, adapted from a recipe by the doyenne of 19th-century Czech cookery, Dobromila Rettigová, is a perennial favorite.

Make a light roux from 2 teaspoons of flour blended into 40 grams of butter. Add 1 liter (1 quart) of stock or broth in a slow, steady stream, constantly whisking. Separately, whisk four egg yolks in a small bowl and slowly blend in 0.5 liter (2 cups) of the hot soup, then pour this mixture back into the soup pot (this prevents the egg from curdling); heat thoroughly, but don't boil. Toward the end of cooking, add 2 tablespoons of cream and a liberal amount of chopped spring herbs — choose from young tops of stinging nettle (Urtica dioica; wear gloves to pick), ground ivy (Glechoma hederacea), daisies (Bellis perennis), primrose (Primula vulgaris), wild strawberry leaves (Frageria vesca) and the green tops of onions or garlic, among others.

Some older recipes for spring soup call for adding cowslip (Primula veris) or violet leaves (Viola odorata), but beware that these wild flowers have become scarce from over-picking and should be left alone to re-establish. Comfrey is another one mentioned in some older literature, but concerns about alkaloids in the plant make it prudent to omit it, at least until more scientific findings are available.

A revitalizing spring salad can be built around a bowlful of store-bought greens spiked with gathered (or purchased) herbs. If, once the weather warms, you're lucky enough to find a big cache of greens such as very young dandelion leaves (Taraxacum officinale; they must not be in flower yet) and chickweed (Stellaria media), you can accent them with more assertive herbs including young plantain leaves (Plantago major), lemony wood sorel (Oxalis acetosella) and peppery yarrow (Achillea millefolium).

For those who want to forage for their spring vitamins, there are a few important rules to follow: First, make sure you have the right plant. Consult a reliable field guide if necessary (go by their Latin names). Gather well away from busy roads, railroad tracks, chemically treated areas and places frequented by dogs or cats. Take only what you will use, and do a thoughtful thinning rather than a quick snatch and grab. Wash everything carefully, and, as with wild mushrooms, start by eating small quantities and slowly increase your intake to unmask any food sensitivities with minimal discomfort.