The 'Mountains' singer was ordered onto bed rest by doctors and he admits he was ''terrified'' when he realised he had reached breaking point.
He said: ''Getting older, my own mortality popped into my mind a lot more. I ended up having a bit of a breakdown.
''I was just about to go into America, through immigration and I had to get taken side and wired up to this heart monitor, strapped into this chair and there were medics all around me.
''It was the most terrifying moment of my life because I felt like my mind and body just broke.
''I was ordered to have bed rest by the doctor because I was just in such a bad state. There was a big change - a forced change - in my personal life. Rather than thinking about the band all the time, I took a big step back and thought about my survival as a human being.''
The 35-year-old rocker admits he even considered giving up music in a bid to get better, but is now feeling stronger than ever.
He told Q magazine: ''I went on holiday and spent some time with my wife.
''Things became very clear to me about how to let my own soul flourish while digging into dark places. I think, as well, just singing really personal songs took their toll and I felt like a bit of a shell of a man and I kind of lost myself. At a certain point I thought, 'Can I be happy and do this? If I'm mining these parts of my mind and soul can I do that and still exist in a healthy place?' I realised I'm not quite as invincible as I thought I was.
''But good old prescriptions can get you through anything. I feel great now.''
Why has pop-punk made a 2020s resurgence?
One of the most diverse line-ups we've seen for a major awards show in a while.
Having formed in 1999, Kings Of Leon went on to release their debut album, Youth & Young Manhood in 2003, but it was in April 2007 when they released...
Will you be logging on for virtual Glastonbury this May?
Her new lingerie photos have divided opinion across the internet.