The first time 16-year-old Mackensie Freeman had the urge to pull out her own hair was in fifth grade.

“I just used my fingers and started pulling out my eyebrows,” she told YouBeauty. When a Google search led her worried parents to the hair-pulling disorder trichotillomania, a compulsive hair pulling disorder, they knew it was time for Mackensie to see a doctor.

Trichotillomania, or TTM or “trich,” is when pullers go strand by strand, consciously or unconsciously, to methodically tear out hair from their heads, brows, eyelashes, or elsewhere on their bodies, often creating bald patches. Sound extreme? Actually, you probably know someone on the trich spectrum: two in 50 people will experience it in their lifetime, according to the Trichotillomania Learning Center. Most begin showing symptoms in late childhood or early puberty, like Mackensie did.

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Trich is what’s known as a “body-focused repetitive behavior” (BFRB), similar to biting your nails. For trich sufferers, sitting still often sets off an episode of prolonged pulling, which is why Mackensie uses fiddle toys (such as beads or squishy toys) to keep from pulling during her 10th grade high school classes. Still, when she does begin pulling out her hair, episodes can last from five minutes to a few hours. Mackensie told YouBeauty:

“I usually give in, unless I’m really working on stopping, which is something I’m trying to do. When I’ve been pulling for awhile, I don’t even remember that I put my hand up to start. I’ll just become conscious in the middle of an episode. By that time, you don’t want to stop.”