Earls (34), has been a stalwart in the Munster and Ireland sides throughout his career, with his 35 international tries putting him second on the all-time national list just behind Brian O’Driscoll.
However, speaking on The Late Late Show on Friday night, Earls revealed that off the pitch, he has struggled with his mental health.
The death of Earls’ 19-year-old cousin in a car accident when he was 12 hit him hard and caused him to suffer a panic attack.
"I was sitting at home on the couch and my parents were at work and I remember thinking 'I wasn't going to see my cousin ever again', and then it just went downhill from there, I was thinking about when I die, I will never see my parents.
"I was shaking, I was trembling and then the panic attack started. I didn't know what it was.
"I genuinely, genuinely thought I was going to die. I came around after a few minutes.
"I kept it all quiet, didn’t really speak about it.
"I suppose the fact I didn't know what it was, I was a small bit embarrassed, maybe. I have had a couple of them out through my career as well and it did take me a long time to talk about stuff."
Earls says that in 2013, after years of negative thoughts, he finally decided to reach out for help, and received the diagnosis of bipolar II.
"I was in camp in 2013. I am in Irish camp, Joe Schmidt is just taking over the Irish team. I should be on cloud nine.
"My daughter, Ella Maye, my first girl, was born in 2012 and she was born with a respiratory condition, and you know my emotions were everywhere. My paranoia was through the roof. My negative thinking, it was shocking, and you know I was so sick of it. It was absolutely draining me.
"So, here I am in Carton House, in Irish camp and I just decided I need to do something about this. So, I rang the doctor… I explained everything to him, he was brilliant.
"I went down to see a guy in Cork, a psychiatrist, and he diagnosed me with bipolar II. There is obviously bipolar I as well, but bipolar II is probably the better out of the two to get. I was delighted to get the diagnosis; I was genuinely losing my mind."
Thankfully, Earls says that that intervention eight years ago has helped him hugely.
"Thankfully over the last couple of years, I have got a great hold on it.
"I have found my identity. Which I think was part of the problem as well. I didn't know who I was, and I was always trying to be other people.
"I didn’t know when I was Keith, I didn’t know when I was Hank (the name he gives to his depressive side). And thankfully I can tell the difference now.
"I wanted to tell my story because…if I can help anyone, even it was in the general public, any one of my team-mates to talk to someone before it gets too late.
"I think that’s what saved me, stepping up and not being embarrassed and speaking to someone and telling someone that I was struggling."