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In an essay for Motto, the "Frozen" star revealed that when she was in college, her otherwise bubbly and positive attitude suddenly turned negative - leaving the sunny actress feeling as though she were "permanently in the shade."
"For me, depression is not sadness. It's not having a bad day and needing a hug," Bell wrote. "Its debilitation was all-consuming, and it shut down my mental circuit board. I felt worthless, like I had nothing to offer, like I was a failure."
Bell's mother had told her about depression when she was 18 - saying that if she ever felt like a dark cloud was following her, she should talk to her family, a therapist or a doctor to get help. And so, when the actress realized she was not being herself, she sought help - and now Bell is hoping others will follow suit.
The actress said she was opening up about her struggles, with the intention of helping to remove the stigmas that still surround depression and anxiety.
Bell wrote that rather than making vulnerable people feel as though they have to keep their mental health issues to themselves, they should feel free to talk about them, and encouraged to seek help.
"Talking about how you're feeling is the first step to helping yourself. Depression is a problem that actually has so many solutions. Let's work together to find those solutions for each other and cast some light on a dark situation," Bell wrote.