For more than decade, she has been obsessively picking at the skin on her legs, chest and face — sometimes for many hours at a time — and she can't find a way to stop.
Hartlin suffers from skin picking disease, a disorder classified for the first time as a distinct entity in the just revised psychiatric bible, the Diagnostic and Statistical Manual of Mental Disorders, or DSM-5.
Skin picking, or dermatillomania as it's formally known, was long considered an offshoot of obsessive-compulsive disorder (OCD). And that has made it difficult for those with the condition to get treatment, or even to have it recognized by many as anything more than a bad habit.
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"I went through years, I just felt so embarrassed and had so much shame," says Hartlin, 26, who began digging at her skin at about age 13. "I thought I was the only one for years, and I think that is the worst part, that disorders such as this feed into that isolation and make it worse."
Often she will pick at her skin — what she perceives as in-grown hairs on her legs, or bumps and blemishes on her chest and arms — without conscious awareness while watching TV or sitting at her computer.
Even sleep brings no respite: "I wake up with blood on my legs. I wake up sometimes and I have blood on my fingers from picking at my legs while I'm asleep."
At other times, the picking is more deliberate, triggered by a trip to the bathroom, where she can get entrenched in an episode she feels powerless to stop.
"It takes up a lot of time. If I don't go to bed at a certain time, by about midnight, then I get stuck in the bathroom for well over an hour," she explains. "But when I was younger, like about 20, I used to get caught up in the bathroom for eight hours.
"And sometimes I didn't realize how much time had passed. Sometimes I did but I was just ... I had to keep going to get that feeling."
She has trouble explaining the feeling: it does seem to relieve anxiety and it has a component of self-gratification, a cathartic sense of accomplishment that she has successfully removed what she sees as defects on her skin.
"I'm in a zone where it's just such a fixation that I can't do anything else. I can't think of anything else or focus on anything else. I have to do that."
Toronto psychiatrist Dr. Peggy Richter says everyone picks at their skin to a certain degree, whether that's popping a pimple, squeezing a blackhead or pulling off a scab.
"This is normal behaviour," says Richter, director of the clinic for OCD and related disorders at Sunnybrook Health Sciences Centre, who specializes in treating skin picking and trichotillomania, or compulsive hair pulling.
"But is this a recurrent problem that we have to work at stopping? No. For most of us, it's an isolated event.
"Whereas for these folks, they may have damaged their skin to such a point that they are significantly distressed and very self-conscious about the impact on their appearance and how others perceive them," Richter says.
"The reality of the impact may be such that they're not comfortable going out on a bad picking day because they have raw red areas on their face, for example, that are painful. So maybe they're calling in sick for work a few days a month after a bad episode."
Among Richter's patients are parents who won't take their children to school after a bad picking bout the night before, and some who have dug at their skin so much they need stitches.
One man, who primarily excavates in-grown hairs in his beard area and often creates deep lesions, began stitching himself with a needle and thread because he got tired of going to the emergency department, she says.
"And he's extremely distressed and very self-conscious and experiencing pain because of it. And he had significant scarring, very significant scarring, with a very real objective impact on his appearance because of it.
"But he could not stop."
Sarah Roberts, a PhD candidate who works with a University of Montreal team that researches obsessive disorders like skin picking, says many of those afflicted don't use only their nails. Implements like nail files and tweezers are also employed to gouge out imperfections in their skin, which can lead to infection.
"The criteria for almost any DSM disorder involves distress or impairment in functioning," Roberts notes. "So we're talking about someone who has to see the doctor because their skin is infected because they picked at it so much."
Richter said the exact cause of dermatillomania isn't known, but it occurs more in families with a history of OCD spectrum disorders, suggesting there is a complex genetic vulnerability to the disorder.
An estimated one to four per cent of the population may have the disorder, with women more often affected. But prevalence studies are not definitive, and indeed research of any kind on the condition is relatively sparse.
Treatment primarily involves cognitive behavioural therapy, specifically habit reversal, says Richter, who has treated about 100 patients with skin picking and hair pulling over the last decade or so. While only about half have recovered fully, overall about 80 to 90 per cent have seen improvement.
"They may still pick but it's more limited, they have a better sense of control," she says, adding that one treatment tactic is introducing "competing responses" such as squeezing a stress ball or clenching one's fists — activities incompatible with picking.
Besides dealing with the physical, there are also emotional issues to tackle — often a long-standing sense of worthlessness and self-disgust, adds Richter.
Those feelings can impair the ability to have relationships, especially with a romantic partner.
"Imagine how you feel about getting into an intimate relationship with a possible serious life partner when your skin looks like you have cigarette burns all over it or raw patches that would make it painful to be touched."
Hartlin, a child and youth care worker, says she avoided dating for a long time, afraid that a guy would discover her secret affliction.
"My actual mantra that I kept saying in my head for years, over and over, was that nobody could accept the mess on my body, let alone the mess inside my head that caused it."
But for the last three years, she has been in a relationship with a man she met online, and a month ago they got engaged.
He is supportive and encouraging, she says, and built her website aimed at helping others with the disorder (www.skinpickingsupport.com). Her self-published book from 2009, "Forever Marked: A Dermatillomania Diary," can be ordered through the site.
Now that the DSM-5 officially recognizes skin picking disease, that should lend legitimacy to people struggling to overcome the disorder and hopefully expanded treatment resources across the country, she says.
"Because I've had so many run-ins with doctors, and other people have as well, other sufferers, of doctors not understanding, of doctors chastising. I had a mental health nurse in my area a few years back, she told me that I needed to 'grow up.'
"Now you can just open up that (DSM-5) book and show this."
Hartlin says her skin picking has been less severe since she "came out," and she advises others with the condition to stop hiding and seek help, perhaps by starting with the Canadian Body Focused Repetitive Behaviours Support Network (www.facebook.com/CanadianBFRB).
"For now I'm spreading the awareness and that's my main goal, because that's what makes me truly happier," she says.
Of course, there's no question she wants to be done for good with the compulsion to rend her skin.
"I've learned to live life with this and be happy," she says. "But if I actually found a way to stop doing this, then that would just be an added bonus in my life."