Former Detroit Red Wings forward Johan Franzen was forced to retire from the NHL three years ago due to concussions and has since been diagnosed with post-traumatic stress disorder, as he battles with depression, severe anxiety, and panic attacks.

"Sometimes my whole world falls apart and I can't see the light in the end of the tunnel," Franzen told Gunnar Nordstrom of SportExpressen. "All I can do then is to sleep and lay in my bed. I take antidepressants and try to feel better again. But it quickly gets dark. Very dark."

The 39-year-old's last NHL contest was Oct. 10, 2015, which was the second game of an attempted comeback from a concussion he sustained in January of the same year.

Franzen has continued to feel the effects of that head trauma in the years since.

"Most of the time I think I am moving in the right direction, but when I have the down periods there is nothing positive. I almost give up then, and it is even worse because you think you have been better for a while," he said.

"It's embarrassing. I can speak to one person and the next day I've forgotten his or her name."

His wife, Cissi, wrote a blog in May about her husband's struggles, describing living with him as "not easy" and "like a rollercoaster."

Franzen believes moving back to his native Sweden from Detroit could help ease some of his pain

"I used to go to the mountains. As soon as I see a mountain I feel better."