Justin Bieber thinks he is "nuts".

The 16-year-old pop star suffers from insomnia and can't stop himself from thinking about his loved ones, career and "God" when his head hits the pillow at night, but believes his problems are a sign of his talent.

He said: "I'm crazy, I'm nuts. Just the way my brain works. I'm not normal. I think differently - my mind is always racing. I'm just...nuts. But I think the best musicians probably are.

"I just turn over all night and think. My mind races. I think about all the things I didn't have time to think about during the day - like family and God and things that should be more important but you don't have time to think about, because you just get caught up in everything else during the day."

Justin is enjoying his worldwide success but he accepts his fame comes at a price and he knows he can't just to whatever he wants and has a responsibility to his fans.

He explained to the February edition of Vanity Fair magazine: "It's hard to really balance myself. A regular kid, if he catches the flu, he just gets to go home. But I can't do that . Everything is important. But, you know, my sanity is important, too. Even if I'm angry, I'll just put a smile on my face and fake it. I don't often fake it - what's me is me. I know I have to give up a lot of myself, or a lot of a private life."

Despite the problems his singing career cause him, the 'Baby' singer won't ever give up on his career and plans to push himself as far as he can.

He said: "I see myself just growing. I didn't know that any of this was really possible. I grew up in a really small town with not a lot of money, and I liked singing, but it was just something that was a hobby. As I get into it more, I want to grow as an artist, as an entertainer, and basically perfect my craft. I want to be the best that I can be."