United Kingdom, April 4 -- Kenan Thompson has been diagnosed with gastroesophageal reflux disease.

The 46-year-old actor was diagnosed with the disease - which causes stomach acid to repeatedly flow back into the tube that connects his mouth to his stomach - after he started experiencing painful heartburn on the set of 'Saturday Night Live' two years ago.

Speaking to PEOPLE, Kenan shared: "I noticed that I would get hoarse a lot easier when I'm doing the show. Losing my voice quicker, but also uncomfortable sleepless nights because I'm burping up acid, just kind of hiccuping all night. And that can definitely add more stress to an already stressful kind of environment doing a live show like that.

"So, all of those factors, I was like w...