Trichotillomania (TTM), a condition that causes sufferers to have overwhelming urges to pull out their own hair, is more common than you might think — it's thought to affect around 110 million people around the world.
One young woman regularly resorts to drastic measures to find some relief from the disorder that has such control over her life.
Rebecca Brown has shared a video to her YouTube channel, TrichJournal, showing herself shaving off the hair that has taken her so long to grow — and it makes for emotional viewing.
"I currently have tonnes of hair on my head but I have so much permanent damage that some of this is not going to grow for another year or so," she says. "It's either shave my hair or lose my hair. I am fed up of being triggered and tortured by the hair on my head and I don't really have any other options — it's so complicated."
Holding back tears Brown uses an electric razor to shave her head.
"Shaving does not stop my disorder. This is not the end of my disorder, but I've kind of been forced to do this," she says when the job is done. "Despite this I've got to keep ploughing forwards. You can't give up with a disorder, even when you hate it you just have to keep going because you can't do anything else. I need a bit of time to process this — this has been so hard to do."
According to the NHS website, trichotillomania is "an impuse-control disorder" and a "psychological condition where the person is unable to stop themselves carrying out a particular action."
It's not restricted to hair-pulling from the head; sufferers may have an urge to pull out hair from other places, such as their eyelashes or eyebrows. After pulling out hair they'll feel a sense of relief.
Impulse-control disorders are more likely to affect girls than boys and are most common among teenagers and young adults but they can begin at any age.
Visit Trichotillomania Support for more information and help.
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