WALTHAM (CBS) – “I slept for basically two weeks straight.”

That was a symptom Hailey Cray expected when she got the coronavirus last December. “Going up the stairs here, it took everything. I would stop halfway up and have to take a deep breath,” she told WBZ-TV.

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She also expected a loss of smell and taste, which did impact her. In fact, she still doesn’t have it back fully, something the 23-year-old says has been a significant source of frustration for someone who loves to cook.

But what she did not expect was a significant and long-term worsening of her depression and anxiety.

“Just a deep sadness set in and I still can’t quite shake it,” she said. “Maybe three weeks after I returned to work and stuff like that when I was starting to expect that I would feel better, and I wasn’t. My body was fine, but my brain was just not — still that tiredness, like I want to just stay in bed and not get out of bed all day.”

And Hailey is convinced her Covid infection is at least partly to blame.

“There’s something neurological going on with Covid, or psychological, too, that I don’t think we quite understand yet,” she said.

Mental health experts increasingly believe Hailey is onto something — that Covid could cause depression and anxiety, even in people who’ve never experienced it at a clinical level before.

“I have seen that in my outpatients,” said Dr. Stephanie Collier, a psychiatrist with McLean Hospital in Belmont.

Researchers, she says, “have looked at cell cultures and they have looked at the direct effects. We think that Covid directly infects the brain. And there also could be a second indirect effect, and that’s inflammation of the immune response.”

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That inflammation could be the key, according to researchers with Massachusetts General Hospital’s Simches Research Center. They’re studying the effects Covid might have on certain brain cells.

“One of the things my lab works on is different kinds of brain cells that we grow from human stem cells,” says Dr. Roy Perlis, professor of psychiatry at Harvard Medical School and a lead researcher at MGH.

He and his team can then take those brain cells and test how the body’s immune response might alter them. Perlis believes a so-called “cytokine storm” kicked off by the coronavirus can change some brain cells. They’re trying to figure out which ones — and how.

“Cells in the brain can respond to that inflammation and as part of that immune response probably do either release other kinds of factors in the brain or change their function in a way that may set people up for more depression,” he says.

Perlis says some studies suggest upwards of 25 percent of people infected with Covid could experience these mood effects, and that men could be more susceptible than women. But, he cautions that we’re still in the early days of understanding Covid’s effects on our psychology.

The good news? Perlis believes those effects are not permanent and might last six months to a year in most patients.

“I’m incredibly optimistic about the long-term prognosis for most people. The brain is incredibly plastic and able to heal itself. We’re wired to be resilient,” he says.

While scientists work on those answers, Hailey has found some success in a combination of talk therapy, anti-depressants and a new friend, her dog Otto.

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“He just makes me happy,” she says.