Michael Douglas says "the sun came out" when his son was released from prison

Speaking to PEOPLE magazine, he said: "It went from feeling [cautious] to relief, to the joy of having Cameron back.

"It's like this huge storm has passed and the sun came out and you can enjoy your life again without looking over your back. It's a wonderful feeling of being complete."

Cameron took cocaine on a daily basis at the height of his addiction and suffered seizures as a result of the drug consumption, despite the best attempts of Michael and Cameron's mother, Diandra Luker.

The 'National Lampoon's Adam and Eve' actor has released a memoir 'Long Way Home' to help other addicts, and his father is "proud" of the way he's fought to overcome his demons.

Michael said: "I'm very proud of him, not only for the book but for the way he conducts his life. He's talking the talk and walking the walk."

Two-time Oscar-winner Michael previously admitted that Cameron's prison sentence could be a "fresh start", while he also assumed blame for Cameron's situation for "being a bad father."

Meanwhile, he has now admitted he had moments where he decided to "protect" himself despite wanting to stand by his offspring.

He explained: "You go from compassion for somebody you love and worry about and you balance that with your own hostility and anger as it begins to increase.

"I remember him looking at me and I said, 'Listen, you know I love you but I am going to protect myself and the family."