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JUSTIN CHAMBERS opens up to People about the sleeping disorder that led the "Grey's Anatomy" star to check in to UCLA Medical Center in January.

"It's an issue that I've had for a while," Justin tells the magazine. "It's a biological sleep disorder. Your mind keeps racing, and your body is tired. It wants to go to sleep, but it can't."

The actor reveals that in the two months prior to his hospital stay, he was sleeping no more than an hour a week. "I got to my wit's end," he says.