Sleep and wakeup of a Beaglebone Black


I want to record dvb-t broadcasts with my BBB
to a sd-card.

I am using Robert Nelsons kernel 3.8.13.

Is it possible to put a Beaglebone black to sleep and
let it wake up at a certain time ?
How much does work already?

Thank you very much in advance for any help!

Best regards,