Kendrick Lamar believes there is a ''thin line'' between sanity and ''losing it''.

The 'm.A.A.d City' hitmaker has admitted he struggles with being separated from his friends and family whilst touring because it is ''out of my control''.

He said: ''When I was on that tour bus and things are happening back home in my city or in my family that I can't do anything about, it's out of my control, [and to] put it in God's hands, I couldn't understand that.

''That can draw a thin line between you having your sanity and you losing it. This is how artists deteriorate if you don't catch yourself.''

The 27-year-old star recalls a particular tragic incident where he was away from home when three of his close friends were murdered.

He added to MTV: ''It's real, man. Three of my homeboys [one] summertime were murdered, close ones too, not just somebody that I hear about. These [are] people I grew up with.

''It all, psychologically, it messes your brain up. You live in this life, you know what I'm saying, but you still have to face realities of this. I gotta get back off that tour bus and go to these funerals ... Talk to my mom and talk to their aunties - the kids that lost their lives.''