Co-star: Duchovny doing well in rehab

David Duchovny is "doing well" since admitting himself into rehab for sex addiction, according to one of his co-stars on hit U.S. TV show 'Californication'.

The 48-year-old - who plays a sex-loving author in the raunchy cable show - checked himself into rehab last month in a bid to control his own sexual urges.