Kristen Bell's depression left her feeling "worthless".
The 35-year-old actress - who has daughters Lincoln, three, and Delta, 17 months, with husband Dax Shepard - struggled with a "complete and utter sense of isolation and loneliness" because of the mental illness and hopes that speaking out about her own issues will help others in a similar situation.
In an essay for Motto, she wrote: "For me, depression is not sadness. It's not having a bad day and needing a hug. It gave me a complete and utter sense of isolation and loneliness. 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. Now, after seeking help, I can see that those thoughts, of course, couldn't have been more wrong. It's important for me to be candid about this so people in a similar situation can realise that they are not worthless and that they do have something to offer. We all do.
"When you try to keep things hidden, they fester and ultimately end up revealing themselves in a far more destructive way than if you approach them with honesty. I didn't speak publicly about my struggles with mental health for the first 15 years of my career. But now I'm at a point where I don't believe anything should be taboo. So here I am, talking to you about what I've experienced."
And Kristen has paid tribute to her mother for helping her to cope with her illness.
She said: "When I was 18, my mom sat me down and said, 'If there ever comes a time where you feel like a dark cloud is following you, you can get help. You can talk to me, talk to a therapist, talk to doctor. I want you to know that there are options.'
"I'm so thankful for her openness on this predominantly silent subject because later, when I was in college, that time did come. I felt plagued with a negative attitude and a sense that I was permanently in the shade. I'm normally such a bubbly, positive person, and all of a sudden I stopped feeling like myself."