(CNN)For Lavinia Darr, a public bus was dangerous territory.
There were the other passengers, who she feared would be aghast at her physical flaws.
And there were the mirrors and windows, which she knew would propel her into deep self-loathing.
Daily commute debilitated the 23-year-old -- because body dysmorphic disorder (BDD) defined so many parts of her daily life.
But one afternoon in a pandemic-rattled 2020, Darr compulsively checked the bus mirror for her flaws and saw a mask instead.
"I couldn't see any of the features I fixate on," she told CNN. "The mask is covering my nose and my jaw, and I was like, 'Wow. My hair is really nice today."
Ordinarily, Darr said, a glimpse of her reflection sends her spiraling into dysmorphic thoughts.
But now, for her and for others struggling with body dysmorphia, wearing masks is making everyday life more bearable.
It's an extreme that can drive some to extremes
BDD is a psychiatric illness in which people are preoccupied with perceived physical flaws to the extent that it impacts daily functioning.
For Darr -- one BDD sufferer among the five to 10 million in the US -- those flaws relate to her chin and nose.
"A jaw that cuts glass," she said, is what she wants. And she compulsively performs body checks to manipulate her face to this end.
"I'm taking my thumbs and I'm drawing them against my jaw to try and make it look different," she said.
Darr's body checking -- whether with her thumbs or in the mirror -- is one compulsion among many. Others with body dysmorphia may pick their skin or seek cosmetic surgeries. In severe cases, sufferers might perform self surgeries and amputations.
Dr. Eda Gorbis has worked with BDD patients since the 1990s and acts as director of the Westwood Institute for Anxiety Disorders, Inc. in Los Angeles.
She said she has seen patients with over 100 plastic procedures in tow.
"It's a very severe medical illness," she said. "The feedback from the eyes and into the brain is not properly processed. They do not see the forest for the trees, so they over-focus on the detail."
Masks help sufferers camouflage themselves - to an extent
For people like Darr, with fixations on her face, masks can ease some of these compulsive symptoms.
"Masks make it easier. This entire year with mask-wearing has been great," she said. "It shields both other people from my mysterious ugliness, and myself."
Gorbis has noticed that many of her patients are relieved by the widespread usage of masks.
She said the pandemic has supported a pre-existing tendency in BDD patients to isolate themselves and hide their features.
"Without the pandemic, they camouflage themselves," Gorbis told CNN. "They don't venture out. So, staying at home for them now is great, and wearing a mask is fantastic."
But, Gorbis said, it's not a long-term solution. Points of fixation for BDD patients are not actually fixed.
"It's like hypochondriasis," she said. "With hypochondriasis, [the obsession] moves from organ to organ -- 'It's my appendix, it's my heart, it's my stomach.' With BDD, it's the body part."
But it's one step toward self-acceptance for some
Eli, a 23-year-old trans man, asked not to be identified by his full name for privacy concerns.
He said he understands that masks are not the sole solution to his problems.
But suffering from both BDD and gender dysphoria, he said that they help him, and others, better affirm his gender identity.
Now more than ever, people are correctly gendering him in public spaces.
"I went into a grocery store in a mask and baggy clothes, and someone tapped me on the shoulder and said 'Excuse me, sir,'" he told CNN. "I don't even remember what they said. All I remember is that they called me 'sir.'"
Unable to take testosterone, Eli said both gender dysphoria and BDD make him fixate on his face.
"I have very soft features and a very soft jaw line," he said. "When I wear a mask, it hides my jawline and I feel a lot more confident."
He said that BDD adds another layer of difficulty when it comes to self-acceptance as a trans person, especially in regards to coming out.
"I fought myself over it for years," he said. "I've come out four different times over the course of my life, and then push myself back into the closet."
Being properly gendered helps, though -- and the way masks facilitate this makes them a "safety blanket," he said, while he works toward self-acceptance.
BDD, however, is notoriously hard to treat
A large piece of BDD treatment though, Gorbis said, is not camouflaging -- it's exposure.
To this end, Gorbis developed "crooked mirrors" to externalize and exaggerate patients' distortions. In treatment, she has her patients face their worst fears -- that they are ugly, and that yes, everyone notices.
"It is so they habituate to the idea that they can be ugly and still acceptable," she said. "Because the brain is going to keep giving them that feedback, that 'You're ugly.'"
Exposure can help BDD patients live with this feedback loop, she said, while other patients find relief in cognitive behavioral therapy, medication or a combination of treatment methods.
Still, she said, many BDD sufferers never even find themselves in treatment -- a dangerous fact, given the severity of the illness.
A 2007 study found that around 80% of people with BDD experience suicidal ideation at some point in their lifetime. About one in four or more have attempted suicide.
The majority of these people cite BDD symptoms as the primary reason for their suicidality.
Hurdles to recovery are lodged in the very nature of BDD as an illness that benefits from shame and secrecy.
But for those who do enter treatment, chances are good.
A 2011 study showed that with enough time, BDD patients frequently make full recoveries and rarely relapse -- signaling a horizon beyond the exhaustion for people like Darr.