Shah Rukh Khan is busy giving the final touches to his much-hyped sci-fi thriller Ra.One and the hectic work schedule has left the actor exhausted.

"So tired can't even hit the bed... can't hit anything. I feel a farishta (angel) watches over my source of energy & resilience. thanx Allah," Shah Rukh wrote on microblogging site Twitter.

The film is slated for release on Diwali.