Her loud reaction to her dreams woke Peeta up with a start, probably saving him from his own freak out. It did cause her knee to knock into his head however, waking him with a painful start, his heart beating rapidly because for a long moment he forgot where he was and why it was so dark.

"What?!" He gasped out from his shock, scrambling to get away from her thrashing as he pushed up and away, the chain binding his hands together rattling far too loudly as he did.