It got so bad that eventually I ended up in a hospital for mental health. I am now 7 1/2 years clean and sober."
The "Stranger Things" star then reflected on how far he's come, noting that he's "grateful" for where he is now.
"I have made many mistakes in my life," he wrote. "But each day is a chance to start again. Atone for mistakes and grow.
"I'm so grateful to be where I am, I'm so grateful to be sober. I'm so grateful to be.
In an interview with i-D magazine in September 2019, Bower -- who was the frontman for the band Counterfeit at the time -- spoke about his recovery.
"I'm in recovery, so one of the first things that they teach you when you're in recovery is to be super honest about what it is that you're feeling," he said.
"The most important thing is, and it's the hardest thing to do, is just express exactly what it is that you're feeling," he added.
While speaking to Upset Magazine, also in September 2019, "The Twilight Saga: New Moon" star explained why he is candid with fans.