BUFFALO — Sabres winger Kyle Okposo said he is fully healthy after a concussion led to sleeping trouble, significant weight loss and a trip to intensive care last March.

Okposo, who played with the Islanders from 2009 through 2016, missed the final few weeks of Buffalo’s season with a previously undisclosed illness. In a letter posted on the team’s website Monday, Okposo said a routine hit in practice caused his mood to change and other problems that required hospitalization.

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The 29-year-old said he lost his appetite, had a negative reaction to sleep medications and that at one point he weighed less than 200 pounds. He spent time in the Neuro Surgical ICU at Buffalo General Hospital to be stabilized. Okposo’s playing weight is listed at 218 pounds.

Okposo played in a 4-on-4 summer league game in Minnesota with other NHL players last week and reported feeling great. New general manager Jason Botterill said Okposo was on track to be ready for training camp.

“I’ve worked with a lot of different people — concussion experts and people who have dealt with concussions themselves — and I feel confident in the fact that I can play hockey again,” Okposo said in the letter. “In fact, I know I can play again. I know I can play and not worry about hitting my head, which is a major hurdle for someone who’s dealt with this. If I didn’t feel 100 percent right now, that probably wouldn’t be the case.”

Okposo’s last NHL game was March 27 against Florida. He had 19 goals and 26 assists for 45 points in 65 games during his first season with Buffalo. He signed a $42 million, seven-year contract with the Sabres last summer.