My Mac stops the renders when it gooes to sleep (power save mode)

Hi!

I'm working with OSX 10.9.1 and AFX 12.2.052.

For the first time in my 15 years working with this great soft, I noticed the renders are going to pause when the Mac goes to sleep (power save mode).

I don't know why the Mac goes to sleep mode when it is redering. Never worked in this way.

Any idea?

thanks a lot.

Juan