In a recent interview, Olivia Munn admitted to suffering from trichotillomania, a disorder that causes an individual to pull out his or her eye-lashes and/or hair.

"I don't bite my nails, but I rip my eyelashes," "The Newsroom" star told the Daily News. "It doesn't hurt, but it's really annoying. Every time I run out of the house, I have to stop and pick up a whole set of fake eyelashes."

Trichotillomania has puzzled experts, and the exact cause of the illness is unknown.

Munn, 32, is one of many celebrities who have struggled with a variation of obsessive-compulsive disorder, an anxiety or psycho-neurotic disorder that causes those with the affliction to be obsessed with certain thoughts, compulsions, or behaviors, which can lead to extreme anxiety or depression.

In some cases, people with OCD cannot think certain thoughts or perform certain acts, and in other cases the opposite holds true and certain thoughts become intrusive, repetitive, and form the basis of compulsive and repetitive behaviors. In still others, there can be a combination of obsessions and compulsions.

Obsessive thoughts can sometimes cause fear, anxiety, and worry, and/or they can sometimes lead to compulsive behaviors acted out to alleve those symptoms. Many OCD sufferers are aware of their compulsive thoughts or behaviors, and this leads to further anxiety.

Here are five who have admitted to facing symptoms of OCD.