Bernie Madoff can’t get anything on credit anymore—not even a prison phone call. Madoff called CNN Money collect for an exclusive interview that was posted on Thursday, telling them that he “can’t sleep” thinking about all of his misdeeds. Madoff said he used to work as a clerk, but now he has been reassigned to telephone and computer systems, but he works only “a few hours” a day, which gives him plenty of time to think. “I was responsible for my son Mark’s death and that’s very, very difficult,” Madoff said. Madoff is serving a 150-year sentence for stealing more than $1 billion from investors in the largest Ponzi scheme in U.S. history.