Jennifer Aniston has started sleepwalking.The actress has recently begun walking around her Los Angeles mansion in a deep sleep and then wake up in a different part of her home, confused and bewildered. Friends of Jennifer, 37, believe she has started sleepwalking because of stress in her personal life.The star split from boyfriend Vince Vaughn - who she met while filming 'TheBreak-Up' in December and pals claim she previously started wandering in her sleep when her marriage to ex-husband Brad Pitt started to disintegrate. One pal is quoted by Britain's 'The Sun' newspaper as saying: "She had the same problems when things started going wrong during her marriage to Brad. One time he freaked out because she disappeared for an hour-and-a-half." Jennifer and Brad split on January 7, 2000, after over four years of marriage, amid allegations Brad had been having an affair with his then 'Mr.and Mrs. Smith' co-star and current partner Angelina Jolie, who he now has a daughter, Shiloh Nouvel, with. Jennifer and Brad officially divorced on October 2, 2005.