File photo of actor Robin Williams arriving for the European premiere of "Happy Feet " at the Empire cinema in London
Actor Robin Williams arrives for the European premiere of "Happy Feet " at the Empire cinema in London in this file picture taken November 26, 2006. Oscar-winning actor and comedian Williams was found dead on Monday from an apparent suicide at his home in Northern California, Marin County Sheriff's Office said. He was 63. REUTERS/Luke Macgregor/Files

Robin Williams, 63, admitted himself to a special unit of the Hazelden Addiction Treatment Center in Lindstrom Minnesota in June this year to manage his addiction. Here, he made quite an impression on his rehab mates, especially to Teresa Cohen, a troubled mom that the actor confided in to. Teresa, whose stay on the center overlapped with Robin's for nine days, claimed that the actor was funny and friendly, always the first to help out whenever needed.

Daily Star UK reported that Robin Williams, even though he was on rehab, was usually his funny self, just like the roles he portrayed on screen. However, Teresa Cohen, one of the friends he made on this stint, shared that it was obvious that something was eating him up inside and making him feel depressed and unhappy.

"It was ­obvious there was something much, much ­deeper going on inside him. Even though he'd goof around from time to time, just like he did on screen, there were many other occasions when his face reflected deep ­depression and unhappiness," shared by the troubled mom to Daily Star UK.

She also claimed that Robin felt stressed whenever he had to put on a happy face for fans. Robin shared to her as much as he loved having his fans around, he hated the fact that he needed to put up a mask and some sort of funny appearance for them.

The veteran actor also admitted to Teresa that he felt tired to the bones and that he could fall asleep even standing up. The troubled-mom-turned-confidante also shared that it was obvious that Robin was feeling mentally and physically horrible.

Despite Robin's troubles, Teresa was quick to say that Robin made everyone's life during rehab easier, always the first to offer help and even listen to others even though he himself is fighting his own demons.

"He was the first person to perform humble chores like setting stacked chairs out for group therapy sessions. Once he spent more than two hours patiently listening to the outpourings of a ­younger guy, also in the ­entertainment business, who was there for the first time and still 'shaking and baking' with hot sweats and jitters from his detox programme. Robin was always ready to help others and was like a father-confessor figure to people he thought weren't coping too well with rehab, which can be a scary, bewildering experience," shared Teresa to Daily Star UK.

Teresa shared that while helping others, Robin never troubled anyone with his own problems. He'd rather help others and medicate himself through his prescription drugs. Mail Online UK had reported that a source close to the actor claimed however that as Robin Williams took a combination of drugs for his depression and Parkinson's, the same drugs might have led to him having suicidal thoughts.