Robin Thicke thinks Santa Claus causes "stress" for parents.

The 'Blurred Lines' singer - who has 14-year-old Julian with ex-wife Paula Patton and Mia, six, Lola, five, and Luca, three, with fiancee April Love Geary - feels it is hard to know the right time to discuss whether Father Christmas really exists and brings presents to all the houses around the world, and admitted he "coaches" his kids to "believe".

He told the New York Post newspaper's Page Six column: "The Santa conversation is a stressful conversation, especially when they get old enough to where the other kids at school [start finding out he's not real].

"And if they go to school with kids of other different religions then the conversation happens a lot earlier."

On how he coaches his kids, Robin said he tells them: "If you believe, Santa will come."

But the 47-year-old singer thinks the idea only lasts "about five or six years".

He added: "Sooner or later that fantasy is over."

Robin's eldest son is now making his own music and the 'My Life' singer was so impressed by one of the tracks he had written that he asked to record his own version - but Julian wouldn't let him.

Speaking on V-103's 'Big Trigger Morning Show', Robin said: "He's got the gift. He's got a great voice [and] head on his shoulders. Recently, he got back into some songwriting … He wrote a song and played it for me. The funny thing is I [say,] 'Man, I really love this new song you wrote. Would you mind if I did a version? I think it'd be really cool if I sang a version of your song,' and he's like, 'But it's my song.' I'm like, 'Okay. I like the swag already'."

And Robin admitted the teenager won't turn to him for advice.

He added: "If [Julian] asked me for advice, which lately he doesn't really even want to, I think he [would] want me to support and praise [him.] So, he wrote a great song and I just praised the heck out of it and told him how proud I am and told him to keep going [and] pushing, and that way he can become his own artist on his own time."