It’s been a long, grueling winter in Chicago. The parks have been abandoned for months, and the dogs are half-crazed with being locked indoors. People’s faces wear the same expressionless gray as the sky.

On the other hand, these have been great months for dessert. For solace from the ice storms, unshoveled sidewalks, and frozen cars, I have turned time and again to comfort desserts — hearty baked goods that ooze sugar and butter: apple crisps, oatmeal cookies, truffle brownies, gingerbread.

I am hardly the only American who relies on favorite desserts to survive tough times. Whether homemade classics or store-shelf favorites, comfort-type desserts are bigger than ever. Perhaps the rabid popularity of Rachel Ray and Paula Deen is due to their predilection for indulgences like Root Beer Bomb, sundaes, apple strudel, and bread pudding.

After a long day at work, watching an apple strudel come together can make for gripping programming.

And with the housing-market doldrums dragging the nation toward recession, many a struggling worker will reach for a donut (or dozen) to sweeten the bad economic news. Comfort foods, including desserts, sell well during hard times. During the last recession, in 2001, Krispy Kreme’s profits shot up markedly.

Why is it that certain desserts provide just the right balm in hard times? In the miserable depths of January, why didn’t I turn to chipped beef sandwiches or brie?

It turns out that food experts, driven by the obesity crisis, have been wondering the same thing.

So to find out what, exactly, gives a comfort dessert its overpowering magnetism, I called Dr. Jordan Le Bel, a professor of food and beverage management at Cornell and an authority on comfort foods.

Comfort foods are a little like Supreme Court Justice Potter Stewart’s famously subjective take on pornography: hard to define, but you know when you taste them. A comfort dessert, Le Bel said, can include almost anything. In fact, Le Bel has even found people who, incredibly, claim baby carrots as a favorite comfort food! (More on that shortly.)

For some people, comfort foods are emotionally charged. In his research, Le Bel found that they have the power to relieve negative emotions — stress, worry, sadness — and to inspire positive emotions like joy and relaxation.

For people like me, dessert is an “emotional crutch” to overcome daily ups and downs — and mostly the downs. A rich, sweet treat lets me eat my way out of those winter blues. This would explain why taste seems to matter less when it comes to comfort desserts. When I’m eating in this emotional mode, all my interest in fine food goes out the window as I develop a deep, passionate need for Little Debbie oatmeal creme pies. I’m like a rat hitting the feed bar in my condo-cage. Deadline? Worry! Snack cake? Better.

And I’m hardly alone in this respect. Research shows that many women and young people also tend to eat their blues in the form of brownies. Men and older people, on the other hand, are more likely to comfort-nosh in the form of a steak or sandwich or soup. It’s not clear why, but one theory is that men are used to having hot foods served to them when they’re feeling low, as a mother or wife would do. At any rate, such foods deliver a burst of positive emotions.

Then there are the carrot-stick folks. “They don’t eat that to alleviate negative emotions,” Le Bel explains. “They eat that to feel better … Whereas the other group was eating the chocolate to forget about the daily stress and worries and other bad mood, this group was like, ‘I eat this and then I feel so much better. I’m really happy. I’m joyful. I feel lighter.’”

So comfort foods can actually make you happy — but only if they’re healthier, more nourishing comfort foods.

The blues aren’t the only thing that sends us scrambling for succor on a plate. Comfort foods also serve as an edible form of nostalgia. A nostalgic comfort food, says Le Bel, is one that “you develop a preference for early on in your childhood years, and you keep eating it because it throws you back to that childhood memory or period … The traditional, nostalgic eater will go for the apple pie a la mode, just like mom used to make, even though mom’s recipe might have gotten lost.”

And in some cases, we are drawn to comfort desserts simply by the pure, sensory delight of a particular delicacy.

“One person in my mind who stands out said watermelon [was their comfort food],” Le Bel told me. “She said, ‘I’m always looking forward to that first watermelon of the season. Every one thereafter doesn’t reproduce the thrill of eating the first one of the season.’”

“There seems to be a tie to season,” he continued. “I’m guessing there might be some physiological reason for this. We tend to forget that our metabolism and our genetic makeup and our brain makeup evolved to face conditions of food scarcity, particularly in winter when it gets cold and we need to layer on the fat. This is something that is somehow still ingrained in our genetic makeup in food choices.

“So what you have in the winter is probably a preference for richer or warm type of stuff, probably to stay warm to protect yourself, and in the summer — watermelon is low fat, low sugar. It’s all water.”

So as spring finally thaws the frozen corners of America, it’s as if we’re cleaning out the nation’s deep freezer. Out come desserts we haven’t seen for months, new flavors of comfort: popsicles, ice cream, and fruit pies. In go the rich, comforting desserts that have kept us through the winter. Goodbye, bread pudding; so long, marshmallow-swirl brownies. I’ll see you in September — or the next time I feel really bad.