The Grammy winner said adjusting to sudden fame led to his struggle, reported Variety.
"I think you need to, when you get into the industry, adjust to [fame], and I didn't adjust because I was constantly working on tour.
"And all the pitfalls that people read about, I just found myself slipping into all of them. Mostly, like, substance abuse," Sheeran said in an interview for Britain's "The Jonathan Ross Show".
In December 2015, the "Thinking Out Loud" singer announced he was taking a year off from his career. He explained during his interview that his struggle was the reason he decided to step away from the limelight.
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The 26-year-old singer said he completely started focusing on his work as he did not want to lose his success to addiction.
"I just focused on other things. I focused on work and I can't work under the influence, I can't write songs under the influence, I can't perform under the influence so the more I worked the less (that happened).
"I've worked my whole life to get to where I am and you can't lose that over something that you do in your spare time. I didn't really notice it was happening. It just started gradually happening and then some people took me to one side and were like, 'Calm yourself down,'. It's all fun to begin with, it all starts off as a party and then you're doing it on your own and it's not so that was a wake-up call and taking a year off," he said.
"I've rekindled with a girl I went to high school with and we live together now and I think that was a real help grounding me. I was a 25-year-old in the music industry on tour so I just needed someone to balance me out.